Imaging lens, recognition device, and information processing device

Abstract

To provide a bright, high-performance, and compact imaging lens, recognition device, and information processing device with a wide-angle field of view capable of recognizing faces. [Solution] The imaging lens 100 is arranged in order from the object side, with an aperture diaphragm S between the first lens L1 and the second lens L2, which are positioned closest to the object. The first lens L1 is a positive meniscus lens with a convex surface facing the object side, the second lens L2 is a negative lens having an inflection point on at least one side, and the third lens L3 is a negative lens with a concave surface on the image plane side and an inflection point in the peripheral part.

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 the general society, the demand for information security has been increasing in order to prevent the leakage of data from information terminals. As a countermeasure for users, the password is made more complex in order to prevent the leakage of information from the information terminal or to limit the use of the information terminal. However, in the conventional information security measures, when the password is made more complex, it becomes difficult for the user to use it, so the security enhancement by 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 density of these near-infrared devices has also been increasing.

[0004] In addition, in recent years, laptops have come to be equipped with a recognition device that recognizes by 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 is mainly one that combines functions such as motion sensing as well as face authentication at the time of login, and not only high performance of the imaging lens but also miniaturized technologies are known (see, for example, Patent Documents 1 and 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, infrared cameras have emerged that can image in the near-infrared band with a dominant wavelength of 850nm or 940nm, as well as those that can image not only the near-infrared band but also the monochrome (visible light) wavelength characteristic of 450nm.

[0007] However, when the imaging lenses described in Patent Documents 1 and 2 mentioned above were applied to recognition devices, their small field of view resulted in a human face (face region) being too small to be imaged on the image sensor, making it difficult for the recognition device to recognize it as a human face. Therefore, they were not suitable for use in recognition devices. For this reason, there was a need for an imaging lens that was smaller than conventional infrared imaging lenses, had an appropriate field of view that allowed the recognition device to recognize faces, was bright, and was high-performance, while satisfying optical performance not only in the near-infrared band but also in the visible light wavelength band.

[0008] This disclosure is made in view of the above, and aims to provide a bright, high-performance, and compact imaging lens, recognition device, and information processing device that are capable of recognizing faces and have an appropriate field of view. [Means for solving the problem]

[0009] To solve the above-mentioned problems and achieve the objective, the imaging lens according to the first aspect of this disclosure comprises a first lens to a third lens arranged in order from the object side, and an aperture diaphragm positioned closest to the object, wherein the first lens is a positive meniscus lens with a convex surface facing the object side, and the second lens has an inflection point on at least one side. Positive It is a lens, and the third lens is, A negative lens that is concave on the image plane side and has an inflection point at the periphery, where the paraxial radius of curvature R of the lens surface on the contracting side of the entire optical system is smallest, and the focal length of the third lens is f3 and the focal length of the entire optical system is f, then condition (1) 0.6 < |f3 / f| < 2.4 ···(1) It satisfies the condition.

[0010] Further, the recognition device according to the second aspect of the present disclosure includes the above imaging lens and an individual imaging element that receives the image formed by the imaging lens and generates an imaging signal.

[0011] Further, the information processing device according to the third aspect of the present disclosure includes the above recognition device.

Advantages of the Invention

[0012] According to the present disclosure, there is an effect that an imaging lens with a wide-angle field angle, bright, high-performance, and small size capable of face recognition by the recognition device can be realized.

Brief Description of the Drawings

[0013] [Figure 1] FIG. 1 is a diagram showing the lens configuration of the imaging lens according to Embodiment 1 of the present disclosure. [Figure 2A] FIG. 2A is an aberration diagram of the imaging lens according to Embodiment 1 of the present disclosure. [Figure 2B] FIG. 2B is the MTF of the imaging lens according to Embodiment 1 of the present disclosure. [Figure 2C] FIG. 2C is a distortion grid of the imaging lens according to Embodiment 1 of the present disclosure. [Figure 3] FIG. 3 is a diagram showing the lens configuration of the imaging lens according to Embodiment 2 of the present disclosure. [Figure 4A] FIG. 4A is an aberration diagram of the imaging lens according to Embodiment 2 of the present disclosure. [Figure 4B] FIG. 4B is the MTF of the imaging lens according to Embodiment 2 of the present disclosure. [Figure 4C] FIG. 4C is a distortion grid of the imaging lens according to Embodiment 2 of the present disclosure. [Figure 5] FIG. 5 is a diagram showing the lens configuration of the imaging lens according to Embodiment 3 of the present disclosure. [Figure 6A] FIG. 6A is an aberration diagram of the imaging lens according to Embodiment 3 of the present disclosure. [Figure 6B]FIG. 6B shows the MTF of the imaging lens according to Embodiment 3 of the present disclosure. [Figure 6C] FIG. 6C shows the distortion grid of the imaging lens according to Embodiment 3 of the present disclosure. [Figure 7] FIG. 7 is a diagram showing the lens configuration of the imaging lens according to Embodiment 4 of the present disclosure. [Figure 8A] FIG. 8A is an aberration diagram of the imaging lens according to Embodiment 4 of the present disclosure. [Figure 8B] FIG. 8B shows the MTF of the imaging lens according to Embodiment 4 of the present disclosure. [Figure 8C] FIG. 8C shows the distortion grid of the imaging lens according to Embodiment 4 of the present disclosure. [Figure 9] FIG. 9 shows the reflectance characteristics of an example of the near-infrared corresponding coat on each lens surface of the first lens to the fourth lens of the imaging lens according to Embodiments 1 to 4 of the present disclosure. [Figure 10] FIG. 10 is a diagram showing a schematic configuration of an information processing apparatus including a recognition apparatus having the imaging lens according to each embodiment of the present disclosure. [Figure 11] FIG. 11 is a diagram showing the schematic configuration of the recognition apparatus in FIG. 10. [Figure 12] FIG. 12 is a block diagram showing a functional configuration of an information processing apparatus including a recognition apparatus having the imaging lens according to each embodiment of the present disclosure. [Figure 13] FIG. 13 is a schematic diagram showing the size of a face displayed on an image captured by a recognition apparatus when the angle of view of the imaging lens used in the recognition apparatus exceeds 80 degrees. [Figure 14] FIG. 14 is a schematic diagram showing the size of a face displayed on an image captured by a recognition apparatus when the angle of view of the imaging lens of the recognition apparatus is 80 degrees or less.

Embodiments for Carrying Out the Invention

[0014] The imaging lens, recognition device, and information processing device related to this disclosure will be described below with reference to the drawings. However, this disclosure is not limited to the embodiments described below. Furthermore, the figures referenced in the following description only provide a schematic representation of the shape, size, and positional relationships to the extent necessary to understand the content of this disclosure. In other words, this disclosure is not limited to the shapes, sizes, and positional relationships exemplified in the figures. Also, the same parts are denoted by the same reference numerals, and detailed descriptions are omitted.

[0015] [Embodiment] Figures 1, 3, 5, and 7 are cross-sectional views showing the lens configurations of the imaging lenses of Embodiments 1 to 4, respectively. In each cross-sectional view, the left side is the object side (front) and the right side is the image side (rear).

[0016] The imaging lens 100 in each embodiment consists of a first lens L1, a second lens L2, and a third lens L3 arranged in order from the object side to the image side, and an aperture diaphragm S (STOP) arranged closer to the object than the first lens L1.

[0017] In Figures 1, 3, 5, and 7, the reference numerals 1 to 7 attached to either the first lens L1 to the third lens L3 or the aperture diaphragm S represent the surfaces of each lens or diaphragm. Hereinafter, these surfaces will be referred to sequentially as surfaces 1 to 7, from the object side towards the image side. Surface 1 is the surface of the aperture diaphragm S. Furthermore, in Figures 1, 3, 5, and 7, the reference numeral CG represents an infrared parallel plate equivalent to one composed of the cover glass of a solid-state image sensor and at least one of various filters. The incident side of the infrared parallel plate CG is referred to as surface 8, and the image side is referred to as surface 9.

[0018] The imaging lens 100 is composed of an aperture diaphragm, a first lens L1, a second lens L2, and a third lens L3 arranged in order from the object side. The imaging lens 100 has the first lens L1 as the positive lens and the second lens L2 as Positive It has the power PositiveThe lens configuration consists of a third lens, L3, which is a negative lens, and positive, negative, and negative lenses arranged in sequence. In this configuration, spherical aberration and coma aberration can be easily corrected, and good telecentricity can also be achieved on the image side.

[0019] The first lens L1 is a positive lens with its convex surface facing the object, and can be either a meniscus lens or a biconvex lens. As shown in the embodiments described later, the material of the first lens L1 can be either plastic or glass.

[0020] The second lens L2 has an inflection point on at least one side and a small thickness ratio. Positive The device is constructed using lenses, but inflection points may be present on both sides. Here, an inflection point on one side refers to a region on either side 4 or side 5 that includes a position 60-80% of the way from the optical axis towards the outer edge relative to the aperture of the second lens L2. The thickness difference ratio is approximately 0.4-0.6.

[0021] The third lens L3 is constructed using a negative lens that is concave on the image plane side and has an inflection point at its periphery. Here, the inflection point at the periphery is the region that includes the position 60-80% of the way from the optical axis towards the outer edge relative to the aperture of the third lens L3 on the plane 7 side.

[0022] The aperture diaphragm S is positioned closest to the object, making it a so-called front-aperture type, which allows for a smaller front element diameter.

[0023] The first lens L1 to the third lens L3, configured in this way, are all aspherical lenses, each possessing a distinctive aspherical shape. Furthermore, by giving the second lens L2 and the third lens L3 shapes with inflection points, aberrations can be highly corrected while keeping the optical thickness (total length) of the imaging lens 100 thin.

[0024] Furthermore, while all lens materials used are optical plastics, glass materials may also be used.

[0025] Figures 2A-2C, 4A-4C, 6A-6C, and 8A-8C show the longitudinal aberration diagrams, MTF, and distortion grids of the imaging lens 100 of Embodiments 1-4, respectively. The spherical aberration diagram shows the amount of spherical aberration 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). In the astigmatism diagram, the solid line S shows the amount of astigmatism in the sagittal image plane, and the dashed line T shows the amount of astigmatism in the tangential image plane. Furthermore, the distortion diagram shows the amount of distortion for the d line only. Angle(deg) indicates the half-angle of view (°). Furthermore, regarding the distortion grid, the thin lines represent the paraaxial (Paraxial FOV) (ideal) grid, and the thick lines represent the actual (Actual FOV) grid. In addition, for MTF, the frequencies are 1 / 4 Ny and 1 / 2 Ny. At 1 / 4 Ny, the five-dot dashed line represents the sagittal image plane MTF, and the coarse dashed line represents the tangential image plane MTF. At 1 / 2 Ny, the three-dot dashed line represents the sagittal image plane MTF, and the fine dashed line represents the tangential image plane MTF.

[0026] Next, the conditions for the imaging lens 100 in each embodiment will be described. In each embodiment, the imaging lens 100 satisfies the following condition (1) when the focal length of the first lens L1 is f1, the focal length of the third lens L3 is f3, and the focal length of the entire optical system is f. 0.6 < |f3 / f| < 2.4 ···(1)

[0027] Condition (1) is a conditional expression relating to the total focal length of the imaging lens 100 and the lens power of the fourth lens L4.

[0028] If |f3 / f| is below the lower limit of condition (1), the overall focal length tends to be shorter, which is advantageous for wider angles of view, but astigmatism tends to be excessive and distortion also tends to be larger, making it difficult to achieve the desired performance. Also, if |f3 / f| is above the upper limit of condition (1), spherical aberration and astigmatism tend to be improved, but the angle of view tends to be narrower, which is undesirable as it does not achieve the desired performance of the present invention. For this reason, the imaging lens 100 can achieve a balance between miniaturization (low profile) and high performance by satisfying condition (1). That is, if condition (1) is not satisfied, when the imaging lens 100 is placed on the bezel of a display panel in a laptop or the like, it cannot be housed within the space of the thickness portion of the bezel or within the space that houses the display panel, causing the imaging lens 100 to protrude from the surface of the bezel or increasing the thickness of the bezel or the display panel. As a result, if condition (1) is not satisfied, when the imaging lens 100 is placed on the bezel or display panel, the thickness of the display panel or bezel increases, which impairs portability and aesthetics.

[0029] Condition (2) is a condition relating to the refractive index of the lenses. When the refractive index of the material of the first lens L1 with respect to the d line is N1, the refractive index of the material of the second lens L2 with respect to the d line is N2, and the refractive index of the material of the third lens L3 with respect to the d line is N3, the following condition (2) is satisfied. N1 ≒ N2 ∩ N1 < N3 (2)

[0030] In each embodiment, the imaging lens 100 has a lens configuration in which the first lens L1 is positive, the second lens L2 is negative, and the third lens L3 is negative, from the object side. Furthermore, the refractive index N1 of the first lens L1 and the refractive index N2 of the second lens L2 are equivalent, and by making the refractive index N3 greater than the refractive index N1, chromatic aberration can be reduced.

[0031] If condition (2) is not met, chromatic aberration tends to be undercorrected, which is undesirable.

[0032] Furthermore, the imaging lens 100 of each embodiment satisfies the following condition (3) when the refractive index of the material of the first lens L1 with respect to the d line is N1. 1.49 <N1<1.55 ···(3)

[0033] If the refractive index N1 is below the lower limit of condition (3), the optical performance will be further improved, but this is undesirable because it will increase the cost. Also, if the refractive index N1 is above the upper limit of condition (3), the optical performance will be affected by chromatic aberration, which is undesirable. Therefore, by satisfying condition (3), the imaging lens 100 can achieve a balance between cost and chromatic aberration, resulting in a bright, high-performance, and compact imaging lens 100.

[0034] Furthermore, the imaging lens 100 of each embodiment satisfies the following condition (4) when the refractive index of the material of the third lens L3 with respect to the d line is N3. 1.63 <N3<1.67 ···(4)

[0035] If the refractive index N4 is below the lower limit of condition (4), or above the upper limit of condition (5), the balance of chromatic aberration is disrupted. Considering the balance between cost and chromatic aberration, satisfying condition (4) makes it possible to realize a bright, high-performance, and compact imaging lens 100.

[0036] Furthermore, the imaging lens 100 of each embodiment satisfies condition (5) when the paraxial radius of curvature on the object side of the first lens is R1 and the paraxial radius of curvature on the image plane side of the third lens is R6. 0.4 < R1 / R6 < 2.6 ···(5)

[0037] If condition (5) is below the lower limit, the astigmatism difference will be large and the astigmatism will tend to be on the negative side, which is undesirable. Conversely, if condition (5) is above the upper limit, the astigmatism difference will be large and the astigmatism will tend to be on the positive side, which is also undesirable. Considering astigmatism, satisfying condition (5) makes it possible to realize a high-performance imaging lens 100.

[0038] Furthermore, the imaging lens 100 of each embodiment satisfies condition (7) when the total optical length is TTL and the image height is IH. 0.85 < TTL / 2*IH < 0.95 (6)

[0039] If the optical length is below the lower limit of condition (6), the optical length tends to be lower compared to the image height, which is advantageous for miniaturization, but aberrations become larger and aberration correction is insufficient, making it undesirable. Also, if the optical length is above the upper limit of condition (6), aberrations are improved, but the overall length tends to increase, which is undesirable.

[0040] Furthermore, the imaging lens 100 of each embodiment satisfies condition (7) when the half-angle of view is ω. 29° < ω < 40° ···(7)

[0041] Condition (7) is the field of view condition for the imaging lens 100 in each embodiment, and determines the appropriate field of view for the imaging lens 100. Considering the face recognition function of an infrared camera using the imaging lens 100, if the field of view is below the lower limit of condition (7), it indicates a telephoto lens and is not suitable as the field of view of the imaging lens. If it is above the upper limit, it becomes a wide angle, which is undesirable because it makes it difficult to recognize a person's face.

[0042] Furthermore, the imaging lens 100 of each embodiment satisfies condition (11) when the focal length of the entire optical system (imaging lens 100) is f and the total length of the optical system (in the longitudinal direction of the imaging lens 100) is OAL. 0.60 <f / OAL<0.90 ···(11)

[0043] Condition (11) is a condition for balancing the focal length f of the entire optical system with the total length OAL. In the imaging lens 100 of each embodiment, if f / OAL is below the lower limit of condition (6), further widening of the angle of view can be achieved, but the front element diameter tends to increase, which may lead to an increase in size. Also, if f / OAL is above the upper limit of condition (11), the total length of the optical system decreases, but widening the angle of view becomes difficult. An imaging lens 100 that satisfies condition (11) can achieve both a smaller size and a wider angle of view.

[0044] Furthermore, in each embodiment, the imaging lens 100 satisfies condition (12) when the total length of the optical system is OAL and the effective optical diameter of the lens (first lens L1) positioned closest to the object is EfD1. 2.2 <OAL / EfD1<3.2 ···(12)

[0045] Condition (12) is a condition for balancing the overall length of the lens and the front element diameter of the lens (first lens L1). If OAL / EfD1 is below the lower limit of condition (12), the optical system will be miniaturized (shortened in the optical axis direction), but it will be difficult to achieve a wide angle of view. If OAL / EfD1 is above the upper limit of condition (12), the performance of the optical system will be improved, but it will be difficult to achieve miniaturization (shortening in the optical axis direction). By satisfying condition (12), the imaging lens 100 can achieve both miniaturization (shortening in the optical axis direction) and high performance.

[0046] Furthermore, the imaging lens of each embodiment satisfies condition (13) when the exit pupil position is EXP and the image height is IH. -1.3 <EXP / IH<-0.90 ···(13)

[0047] Condition (13) is the condition for optimizing the angle of incidence of light rays on the image plane. When EXP / IH is below the lower limit of condition (13), the angle of incidence of light rays tends to be low, but it tends to be difficult to shorten the overall length of the optical system and miniaturize it. Conversely, when EXP / IH is above the upper limit of condition (13), the angle of incidence of light rays tends to be high. For this reason, the imaging lens 100 can be miniaturized by satisfying condition (13).

[0048] Furthermore, the imaging lenses of each embodiment satisfy condition (14) when the focal length of the first lens L1 is f1 and the focal length of the second lens L2 is f2. |f1 / f2| < 1.8 ···(14)

[0049] Condition (14) concerns the balance of the focal lengths of the first lens L1 and the second lens L2. If the |f1 / f2| condition is greater than or equal to the upper limit of (14), astigmatism tends to increase, which is undesirable. Therefore, the imaging lens 100 can achieve high performance by satisfying condition (14).

[0050] Furthermore, the imaging lens 100 of each embodiment satisfies condition (15) when the focal length of the first lens L1 is f1 and the focal length of the third lens L3 is f3. -1.6 < f1 / f3 < -0.2 (15)

[0051] Condition (15) is a conditional equation relating to the positive power of the first lens L1 and the negative power of the third lens L3. If f1 / f3 is below the lower limit of condition (15), astigmatism tends to be underexposed, and distortion and coma aberration also occur significantly, making it difficult to achieve the desired performance. Also, if f3 / f1 is above the upper limit of condition (15), spherical aberration tends to be overexposed, disrupting the balance with astigmatism and making it difficult to achieve the desired performance.

[0052] Furthermore, the imaging lens 100 in each embodiment has a near-infrared compatible coating on the surface of each of the first lens L1 to third lens L3. lineIt has a compatible coating (layer coating). This near-infrared compatible near-infrared line The compatible coating transmits light in the 450-940nm band and at least near-infrared light. line The reflectivity in the 850nm to 940nm band is 2% or less.

[0053] Figure 9 shows the near-infrared region on the lens surface of each of the first lens L1 to third lens L3 of the imaging lens 100 according to Embodiments 1 to 4. line This is the reflectance characteristics of an example of a compatible coating. In Figure 9, the horizontal axis represents the wavelength band, and the vertical axis represents reflectance. In Figure 9, curve K1 shows the reflectance characteristics of a typical multi-coat, and curve K2 shows the near-infrared... line Compatible coating (near infrared) line This shows the reflectivity characteristics of the corresponding multi-coating.

[0054] On the lens surfaces of the first lens L1 to the third lens L3 of the imaging lens 100, there is a curve K shown in Figure 9. 2 Near-infrared with reflectance characteristics as shown line The corresponding coating (solid line) is applied (coated or layered) to the lens. Such near-infrared line By applying a corresponding coating to the lens surface (coating or lamination), it becomes possible to realize an imaging lens that also supports near-infrared light, and an imaging device equipped with such an imaging lens. The near-infrared region-compatible coatings on the surface of each of the first lens L1 to the third lens L3 are formed by being attached using well-known techniques. line You may also attach a sheet with the corresponding coating.

[0055] The imaging lens 100 in the embodiment of this disclosure has a three-element configuration, resulting in six lens surfaces. The transmittance of the imaging lens 100 is an important factor for both the imaging device and the recognition device.

[0056] Here, if we simply calculate the transmittance of the three-element imaging lens 100 in embodiments 1 to 4 of this disclosure at near-infrared 940 nm, in the case of a three-element configuration, there are six reflective surfaces, so it becomes (1 - reflectance)^6. Therefore, in the case where a typical multi-coating (dotted line) shown in curve K1 of Figure 9 is applied, if the reflectance at 940 nm is 33%, the transmittance at 940 nm = (1 - 0.33)^6 = 9.0%, which is undesirable.

[0057] On the other hand, as shown by curve K2 in Figure 9, near-infrared line Similarly, when calculating the transmittance at 940nm for the corresponding multi-coated lens (curve K2), if the reflectance at 940nm is 2% (see straight line H1), the transmittance at 940nm = (1-0.02)^6 = 88.6%, which is a good transmittance and suitable as imaging lens 100 for an imaging device capable of near-infrared imaging.

[0058] Therefore, the imaging lens 100 in each embodiment 1 to 4 has near-infrared light in each of the first lens L1 to third lens L3. line Corresponding near-infrared line The corresponding multi-coating is applied to the lens surface, transmitting light in the 450-940nm band, and having a reflectance of 2% or less in at least the near-infrared region of 850nm-940nm. As shown by curve K2 in Figure 9, near-infrared line While the reflectivity of the corresponding multi-coating is low even in the visible light band of 450-650nm, considering the sensor characteristics (image sensor characteristics) of the near-infrared imaging device, a reflectivity of 2% or more in the visible light band is acceptable.

[0059] Furthermore, the cover glass described in each embodiment 1 to 4 is coated with an infrared-compatible multi-coating with a reflectivity of 2% or less in the near 850 to 940 nm band, as shown in Figure 9, and is compatible with near-infrared imaging devices.

[0060] [Imaging device] Next, an embodiment of an information processing device (PC) equipped with a recognition device that uses the imaging lens 100 of each embodiment as an imaging optical system will be described.

[0061] Figure 10 is a diagram showing the schematic configuration of an information processing device equipped with a recognition device having an imaging lens 100 according to each embodiment. Figure 11 is a diagram showing the schematic configuration of the recognition device in Figure 10. Figure 12 is a block diagram showing the functional configuration of an information processing device equipped with a recognition device having an imaging lens according to each embodiment.

[0062] The information processing device 30 shown in Figures 10 to 12 comprises at least a recognition device 31, a signal processing device 32, an image processing device 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.

[0063] The recognition device 31 generates an imaging signal by imaging a predetermined field of view under the control of the control unit 34, and outputs this imaging signal to the signal processing unit 32. As shown in Figure 11, the recognition device 31 comprises at least a cover 311, an imaging lens 100 of each embodiment, and a solid image sensor 312. The recognition device 31 is arranged on the front side of the information processing device 30. Specifically, the recognition device 31 is arranged in parallel with the imaging device 40.

[0064] The cover 311 is constructed using a cover glass or the like, which is a component for protecting the imaging lens 100 from dirt and dust.

[0065] The solid-state image sensor 312 receives the image of the object to be imaged formed by the imaging lens 100 and generates an imaging signal by performing photoelectric conversion. The solid-state image sensor 312 is constructed using a CCD sensor, a CMOS sensor, or the like. Preferably, the solid-state image sensor 312 has effective pixels of 8 million pixels or more, so-called 4K or higher (3840 x 2160 or higher), arranged in a two-dimensional matrix.

[0066] The signal processing unit 32, under the control of the control unit 34, performs A / D conversion and other processing on the imaging signal input from the solid image sensor 312 to convert 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). The signal processing unit 32, under the control of the control unit 34, also performs A / D conversion and other processing on the imaging signal input from the imaging device 40 to convert it into a digital imaging signal and outputs it to the image processing unit 33.

[0067] The image processing unit 33, under the control of the control unit 34, performs predetermined image processing on the digital imaging signal input from the signal processing unit 32 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). Here, predetermined image processing includes electrical correction processing of shading, white balance adjustment processing, cropping processing of the central part of the image, and noise reduction processing.

[0068] The control unit 34 controls each component of the information processing device 30. The control unit 34 includes a processor and memory. The processor is configured using a CPU or FPGA (Field-Programmable Gate Array), etc. The memory is configured using RAM (Random Access Memory) or ROM (Read Only Memory), etc. The control unit 34 performs a user face recognition process by performing a well-known pattern matching on the feature information indicating the features of the user's face stored in the storage unit 36 ​​and the imaging signal captured by the recognition device 31, which is input via the image processing unit 33.

[0069] The display unit 35 displays, under the control of the control unit 34, video footage being captured, captured images, still images corresponding to image signals stored in the storage unit 36, and various information related to the information processing device 30, all processed by the image processing unit 33. The display unit 35 also includes a display panel 351 for displaying images and a bezel portion 352 provided around the display panel. The imaging device 31 is positioned in the bezel portion 352. Specifically, the imaging device 31 is positioned with the object side facing the bezel portion 352 on the side facing the user when the information processing device 30 is in use. The thickness of the bezel portion 352 is approximately 5.0 mm, and the imaging lens is required to have a thickness that takes this into account, but the imaging lens of the present invention can be applied to that thickness.

[0070] The storage unit 36 ​​stores various information related to the information processing device 30, programs executed by the information processing device 30, and imaging signals (RAW data and JPEG data) captured by the imaging device 40. The storage unit 36 ​​is constructed using flash memory, SSD (Solid State Drive), HDD (Hard Disk Drive), and memory cards, etc.

[0071] The communication unit 37, under the control of the control unit 34, transmits the imaging signal captured by the imaging device 40 to the outside via the network in accordance with a predetermined communication standard, and receives various information input from the outside. The communication unit 37 uses communication standards that comply with, for example, 4G, LTE, 5G, WiMAX, and Wi-Fi (registered trademark) established by 3GPP (registered trademark) and IEEE.

[0072] The input unit 38 receives user 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, keyboard, mouse, etc.

[0073] The audio input / output unit 39, under the control of the control unit 34, receives external sound input, converts it into an audio signal, and outputs it to the storage unit 36 ​​or the communication unit 37. The audio input / output unit 39, under the control of the control unit 34, also converts audio signals input from the storage unit 36 ​​or the communication unit 37 and outputs them externally. The audio input / output unit 39 is configured using a microphone and a speaker, etc.

[0074] The imaging device 40 generates an imaging signal by imaging a predetermined field of view under the control of the control unit 34, and outputs this imaging signal to the signal processing unit 32. The imaging device 40 is positioned on the front side of the information processing device 30. Specifically, the imaging device 40 is positioned so as to be able to image the user of the information processing device 30. Of course, the position of the imaging device 40 can be appropriately changed depending on the shape, size, and usage of the information processing device 30.

[0075] The information processing device 30 configured in this way can perform face recognition and other functions with external devices using a recognition device 31 having an imaging lens 100, with high image quality of 360,000 pixels or more, and can also communicate via Web communication over a network.

[0076] Here, we will explain a comparison between the field of view of the imaging lens 100 used in the recognition device 31 and an imaging lens with a field of view exceeding 80°.

[0077] Figure 13 is a schematic diagram showing the size of a face displayed on image P1 captured by the recognition device 1 when the field of view of the imaging lens used in the recognition device 31 exceeds 80 degrees. Figure 14 is a schematic diagram showing the size of a face displayed on image P1 captured by the recognition device 31 when the field of view of the imaging lens 100 of the recognition device 31 is 80 degrees or less. In Figure 14, the field of view of the imaging lens 100 is assumed to be approximately 60 degrees.

[0078] As shown in image P1 of Figure 13, when the field of view of the imaging lens used in the recognition device 31 exceeds 80 degrees, the field of view 501 of the imaging lens is too wide, causing the human face 500 formed on the image sensor to become smaller. As a result, the recognition device 31 using an imaging lens with a field of view exceeding 90 degrees will find it difficult to recognize the human face 500 (face area) as a human face because it is too small.

[0079] In contrast, as shown in image P1 of Figure 14, when the field of view of the imaging lens 100 used in the recognition device 31 is approximately 60 degrees, the human face 500 formed on the image sensor becomes larger. As a result, the recognition device 31 using the imaging lens 100 can easily recognize human faces. That is, because the area occupied by the human face 500 in image P1 is large, the control unit 34 can perform pattern matching for the human face 500 with high accuracy.

[0080] In this embodiment, a PC was used 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 also be applied to a webcam or the like that can communicate with a PC via wired or wireless connection.

[0081] According to the embodiments described above, it is possible to achieve a wide-angle view, brightness, high performance, and compact size.

[0082] Furthermore, according to this embodiment, a field of view of approximately 60 to 80 degrees (half-angle of view ω of approximately 30 to 40°) can be achieved with four lenses.

[0083] Furthermore, according to the three implementation forms, the imaging lens 100 can be made to have a wide angle of view, a small F-number, high performance, and a compact size, so in the case of video shooting, it can handle shooting in various environments such as dark environments and can also handle high-speed shooting.

[0084] Furthermore, according to this embodiment, a wide-angle field of view, brightness, high performance, and compact size can be realized, thereby improving the matching between the incident angle at the photodetector of the solid-state image sensor and the light rays incident on the photodetector surface.

[0085] Furthermore, according to this embodiment, it is possible to construct a bright, high-performance, and compact lens with a half-angle of approximately 30° using three elements. Therefore, it can be used as a fixed-focus lens for mobile phones such as smartphones or PCs, thus meeting the performance requirements for recognizing human faces.

[0086] Furthermore, according to this embodiment, a bright, high-performance, and compact lens with a half-angle of view of approximately 30° can be constructed using three lenses. This allows for a shorter overall length in the optical axis direction of the imaging lens 100, as well as a smaller lens diameter, resulting in miniaturization. Consequently, the refractive power of the miniaturized lens is reduced, and the effects of manufacturing and assembly errors are minimized. As a result, productivity can be improved, and production costs can be reduced.

[0087] Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the information processing apparatus according to the embodiments of this disclosure. For example, some components may be deleted from all the components described in the information processing apparatus according to the embodiments of this disclosure described above. In addition, the components described in the information processing apparatus according to the embodiments of this disclosure described above may be appropriately combined.

[0088] Furthermore, in the information processing apparatus according to the embodiments of this disclosure, the "parts" described above can be replaced with "means" or "circuits," etc. For example, the control unit can be replaced with control means or control circuit.

[0089] Furthermore, the program to be executed by the information processing device according to the embodiments of this disclosure is provided as file data in an installable or executable format, recorded on a computer-readable recording medium such as a CD-ROM, flexible disk (FD), CD-R, DVD (Digital Versatile Disk), USB media, or flash memory.

[0090] Furthermore, the program to be executed by the information processing device according to the embodiment of this disclosure may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. [Examples]

[0091] Examples 1 to 4 of the imaging lens 100 corresponding to each of Embodiments 1 to 4 are shown below. The meaning of the symbols in each example is as follows: f: Focal length of the entire lens system fl: Focal length of each lens FNo.: Numerical Number (F-number) R: Radius of curvature of the surface D: Surface spacing Nd: Refractive index for d line Vd: Abbe number for the d line SD: Effective Radius An aspherical surface is expressed by the well-known equation (20), where X is the depth in the optical axis direction, H is the height from the optical axis, R is the radius of paraxial curvature, k is the cone constant, and CN (N= an even number greater than or equal to 4) is the higher-order aspherical coefficient. X=(H 2 / R) / [1+{1-k(H / r) 2} 1 / 2 ] +Σ N=4:even CNH N ...(20) Here N≧4:even This represents the sum of all even numbers where N is 4 or greater.

[0092] [Example 1] f=1.5mm, FNo.=2.0, ω=36° The data for Example 1 is shown in Table 1.

[0093] [Table 1]

[0094] The data for aspherical surfaces is shown below. [Table 2] In the above notation for aspherical surfaces, for example, "2.7136.E-02" means "2.7136*10-2". The same applies to the other examples below.

[0095] The parameter values ​​for each condition are as follows. Table 3 also includes information on EP (Entrance Pupil Position). [Table 3]

[0096] This table includes conditions (1) through (7), as well as (11) through (15) for reference. [Table 4]

[0097] Furthermore, in each embodiment, aspherical elements are used in the first lens L1 to the third lens L3, and aberrations are effectively corrected by the aspherical elements.

[0098] Figures 2A to 2C show the aberration diagram, MTF, and distortion grid for the above-described Example 1. As is clear from each figure, the performance is good.

[0099] [Example 2] f=1.7mm, FNo.=2.0, ω=32° The data for Example 2 is shown in Table 5.

[0100] [Table 5]

[0101] The data for aspherical surfaces is shown below. [Table 6]

[0102] The parameter values ​​for each condition are as follows: [Table 7] [Table 8]

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

[0104] [Example 3] f=1.9mm, FNo.=2.0, HFOV=30° The data for Example 3 is shown in Table 9.

[0105] [Table 9]

[0106] The data for aspherical surfaces is shown below. [Table 10]

[0107] The parameter values ​​for each condition are as follows: [Table 11]

[0108] [Table 12]

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

[0110] [Example 4] f=1.4mm, FNo.=2.0, HFOV=40° The data for Example 4 is shown in Table 13. [Table 13]

[0111] The data for aspherical surfaces is shown below. [Table 14]

[0112] The parameter values ​​for each condition are as follows: [Table 15]

[0113] [Table 16]

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

[0115] As shown in Examples 1-4 and Figures 2A-2C, 4A-4C, 6A-6C, and 8A-8C, the imaging lens 100 of this disclosure is bright, high-performance, and compact (shortened in the optical axis direction), achieving a half-angle of view of approximately 30-40° with a three-lens configuration, and is clearly suitable for imaging devices, especially those for laptop PCs.

[0116] Although some embodiments of this application have been described in detail above with reference to the drawings, these are illustrative examples, and the present invention can be implemented in various other forms with modifications and improvements based on the knowledge of those skilled in the art, starting with the embodiments described in the disclosure section of the present invention.

[0117] 30 Information Processing Devices 31 Recognition device 100 imaging lens L1 First Lens L2 Second Lens L3 3rd lens S Aperture diaphragm CG cover glass

Claims

1. The first to third lenses are arranged in order from the object side, The aperture diaphragm positioned closest to the object, Composed of, The first lens is, It is a positive meniscus lens with the convex side facing the object. The second lens is, A positive lens having an inflection point on at least one side, The third lens is, It is a negative lens that is concave on the image plane side and has an inflection point at the periphery, and the paraxial radius of curvature R of the lens surface on the contracting side of the entire optical system is the smallest. When the focal length of the third lens is f3, the focal length of the entire optical system is f, the paraxial radius of curvature of the first lens on the object side is R1, and the paraxial radius of curvature of the third lens on the image plane side is R6, then conditions (1) and (5)' 0.6 < | f3 / f | < 2.4 ... (1) 1.59≦R1 / R6≦1.64...(5)' Satisfied, Each of the first to third lenses is, The lens surface is coated with a near-infrared compatible coating. The aforementioned near-infrared responsive coating is It transmits light in the 450-940 nm band, and has a reflectance of 2% or less in at least the near-infrared region of 850 nm-940 nm. Imaging lens.

2. 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, the refractive index of the material of the second lens with respect to the d line is N2, and the refractive index of the material of the third lens with respect to the d line is N3, then condition (2) N1 = N2 ∩ N1 < N3...(2) Satisfying, 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, condition (3) 1.49 < N1 < 1.55 (3) Satisfying, Imaging lens.

4. The imaging lens according to claim 1, When the refractive index of the material of the third lens with respect to the d line is N3, condition (4) 1.63 < N3 < 1.67 (4) Satisfying, Imaging lens.

5. The imaging lens according to claim 1, When the total optical length is TTL and the image height is IH, condition (6) 0.85 < TTL / 2*IH < 0.95...(6) Satisfying, Imaging lens.

6. The imaging lens according to claim 1, When the field of view is ω, condition (7) 29 < ω < 40 (7) Satisfying, Imaging lens.

7. The imaging lens according to claim 1, A solid-state image sensor that receives the image formed by the imaging lens and generates an imaging signal, Equipped with, recognition device.

8. The recognition device comprises the recognition device described in claim 7. Information processing device.

9. An information processing apparatus according to claim 8, It further includes a display unit for displaying images, The aforementioned display unit is A display panel that displays images, A bezel portion is provided around the aforementioned display panel, Equipped with, The aforementioned recognition device is The bezel portion is arranged as follows: Information processing device.

Images