Imaging lens, imaging device, and information processing device

Abstract

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

Description

[Technical Field]

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

[0002] BACKGROUND ART In recent years, imaging devices such as digital still cameras, digital camcorders, and smartphone cameras that include solid-state imaging elements such as CCDs (Charge Coupled Devices) and CMOSs (Complementary Metal Oxide Semiconductors) and imaging lenses have become widespread.

[0003] The solid-state imaging elements used in these imaging devices are becoming increasingly more pixelated, and as the number of pixels of these solid-state imaging elements increases, imaging lenses are also being required to have higher optical performance.

[0004] Furthermore, in recent years, PCs (Personal Computers) equipped with imaging devices have been used to distribute videos and perform communication over the Web. For this reason, imaging devices have been made smaller in size to facilitate portability. The imaging devices required in the market are primarily those that combine high performance with small size, and imaging lenses are also required to be not only high performance but also small in size. For this reason, imaging lenses that combine high performance with small size are known (see, for example, Patent Document 1 and Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2017-513034 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-106155 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, when distributing videos or communicating over the web, there has been a demand for imaging lenses that can capture images with a wider angle of view than conventional imaging lenses. For this reason, there has been a demand for imaging lenses that are brighter, have higher performance, and are smaller in size than conventional imaging lenses, with a wider angle of view than conventional imaging lenses.

[0007] The present disclosure has been made in view of the above, and has an object to provide a wide-angle, bright, high-performance, and compact imaging lens, an imaging device, and an information processing device. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, an imaging lens according to a first aspect of the present disclosure includes a first lens to a fourth lens arranged in order from the object side, and an aperture stop closest to the object side, wherein the first lens is a positive meniscus lens with a convex surface facing the object side, the second lens has an inflection point on at least one surface and is a lens with a small thickness deviation ratio, the third lens is a positive lens with a convex surface facing the image plane side and an inflection point on the lens periphery, and the fourth lens is a negative lens with a concave surface facing the image plane side and an inflection point on the periphery, and wherein, 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) are satisfied. 0.45 < |f / f1| < 0.80 ···(1) 0.25 < |f4 / f1| < 0.50 ···(2) Satisfy.

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

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

[0011] The present disclosure provides an advantageous effect of providing a bright, high-performance, and compact imaging lens with a wide angle of view. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing a lens configuration of an imaging lens according to a first embodiment of the present disclosure. [Figure 2A] FIG. 2A is an aberration diagram of the imaging lens according to the first embodiment of the present disclosure. [Figure 2B] FIG. 2B shows the MTF of the imaging lens according to the first embodiment of the present disclosure. [Figure 2C] FIG. 2C shows a distortion grating of the imaging lens according to the first embodiment of the present disclosure. [Figure 3] FIG. 3 is a diagram showing a lens configuration of an imaging lens according to a second embodiment of the present disclosure. [Figure 4A] FIG. 4A is an aberration diagram of the imaging lens according to the second embodiment of the present disclosure. [Figure 4B] FIG. 4B shows the MTF of the imaging lens according to the second embodiment of the present disclosure. [Figure 4C] FIG. 4C shows a distortion grating of an imaging lens according to a second embodiment of the present disclosure. [Figure 5] FIG. 5 is a diagram illustrating a lens configuration of an imaging lens according to the third embodiment of the present disclosure. [Figure 6A] FIG. 6A is an aberration diagram of the imaging lens according to the third embodiment of the present disclosure. [Figure 6B] FIG. 6B shows the MTF of the imaging lens according to the third embodiment of the present disclosure. [Figure 6C] FIG. 6C shows a distortion grating of an imaging lens according to a third embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram showing a lens configuration of an imaging lens according to the fourth embodiment of the present disclosure. [Figure 8A] FIG. 8A is an aberration diagram of the imaging lens according to the fourth embodiment of the present disclosure. [Figure 8B]FIG. 8B shows the MTF of the imaging lens according to the fourth embodiment of the present disclosure. [Figure 8C] FIG. 8C shows a distortion grating of an imaging lens according to the fourth embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram showing a lens configuration of an imaging lens according to a fifth embodiment of the present disclosure. [Figure 10A] FIG. 10A is an aberration diagram of the imaging lens according to the fifth embodiment of the present disclosure. [Figure 10B] FIG. 10B shows the MTF of the imaging lens according to the fifth embodiment of the present disclosure. [Figure 10C] FIG. 10C shows a distortion grating of the imaging lens according to the fifth embodiment of the present disclosure. [Figure 11] FIG. 11 is a diagram illustrating a lens configuration of an imaging lens according to the sixth embodiment of the present disclosure. [Figure 12A] FIG. 12A is an aberration diagram of the imaging lens according to the sixth embodiment of the present disclosure. [Figure 12B] FIG. 12B shows the MTF of the imaging lens according to the sixth embodiment of the present disclosure. [Figure 12C] FIG. 12C shows a distortion grating of an imaging lens according to the sixth embodiment of the present disclosure. [Figure 13] FIG. 13 is a diagram illustrating a lens configuration of an imaging lens according to the seventh embodiment of the present disclosure. [Figure 14A] FIG. 14A is an aberration diagram of the imaging lens according to the seventh embodiment of the present disclosure. [Figure 14B] FIG. 14B shows the MTF of the imaging lens according to the seventh embodiment of the present disclosure. [Figure 14C] FIG. 14C shows a distortion grating of the imaging lens according to the seventh embodiment of the present disclosure. [Figure 15] FIG. 15 is a diagram illustrating a lens configuration of an imaging lens according to the eighth embodiment of the present disclosure. [Figure 16A] FIG. 16A is an aberration diagram of the imaging lens according to the eighth embodiment of the present disclosure. [Figure 16B]FIG. 16B shows the MTF of the imaging lens according to the eighth embodiment of the present disclosure. [Figure 16C] FIG. 16C shows a distortion grating of an imaging lens according to the eighth embodiment of the present disclosure. [Figure 17] FIG. 17 is a diagram illustrating a lens configuration of an imaging lens according to a ninth embodiment of the present disclosure. [Figure 18A] FIG. 18A is an aberration diagram of the imaging lens according to the ninth embodiment of the present disclosure. [Figure 18B] FIG. 18B shows the MTF of the imaging lens according to the ninth embodiment of the present disclosure. [Figure 18C] FIG. 18C shows a distortion grating of an imaging lens according to the ninth embodiment of this disclosure. [Figure 19] FIG. 19 is a diagram illustrating a lens configuration of an imaging lens according to a tenth embodiment of the present disclosure. [Figure 20A] FIG. 20A is an aberration diagram of the imaging lens according to the tenth embodiment of the present disclosure. [Figure 20B] FIG. 20B shows the MTF of the imaging lens according to the tenth embodiment of the present disclosure. [Figure 20C] FIG. 20C shows a distortion grating of an imaging lens according to the tenth embodiment of the present disclosure. [Figure 21] FIG. 21 is a diagram showing a schematic configuration of an information processing device including an imaging device having an imaging lens according to each embodiment of the present disclosure. [Figure 22] FIG. 22 is a diagram showing a schematic configuration of the imaging device of FIG. [Figure 23] FIG. 23 is a block diagram showing a functional configuration of an information processing device including an imaging device having an imaging lens according to each embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] An imaging lens, an imaging device, and an information processing device according to the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to the following embodiments. Furthermore, the drawings referred to in the following description merely show a rough outline of the shape, size, and positional relationship to the extent that the contents of the present disclosure can be understood. In other words, the present disclosure is not limited to only the shape, size, and positional relationship exemplified in each drawing. Furthermore, the same parts are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0014] [Embodiment Mode] 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19 are cross-sectional views showing the lens configurations of the imaging lenses of Embodiments 1 to 10. 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, which are arranged in this order from the object side to the image side. The imaging lens 100 also includes an aperture stop S (STOP) which is arranged closer to the object side than the first lens L1.

[0016] In Figures 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19, the reference numerals 1 through 9 attached to the first lens L1 through the fourth lens L4 and the aperture diaphragm S represent the surfaces of the respective lenses or diaphragms. Hereinafter, these surfaces will be referred to as surfaces 1 through 9, sequentially, from the object side to the image side. Surface 1 is the surface of the aperture diaphragm S. Furthermore, in Figures 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19, the reference numeral CG represents a transparent plane-parallel plate equivalent to a solid-state image sensor cover glass and at least one of various filters. The incident side of the transparent plane-parallel plate CG is referred to as surface 10, and the image side is referred to as surface 11.

[0017] Imaging lens 100 is composed of, in order from the object side, an aperture stop S and first to fourth lenses L1 to L4. In imaging lens 100, first lens L1 is a positive lens, and the second lens has either positive or negative power. In imaging lens 100, the third lens is a positive lens, and the fourth lens is a negative lens. Furthermore, in imaging lens 100, the lens closest to the object side is a positive lens, and the lens closest to the image plane side is a negative lens. With this type of lens configuration, the incident angle of light rays tends to be low, and the exit angle of light rays becomes large at the negative lens of the final lens, the fourth lens L4, but by optimizing the power balance of the lenses, good telecentricity on the image side can be achieved.

[0018] The first lens L1 is a positive meniscus lens with a convex surface facing the object side, and may have an inflection point in the peripheral portion of the lens on the image side. Here, the inflection point in the peripheral portion refers to a region that includes 60 to 80 percent of the position from the optical axis toward the outer edge of the aperture of the first lens L1 on the surface 2 side.

[0019] The second lens L2 has an inflection point on at least one surface and is configured using a positive or negative lens with a small thickness deviation ratio, but may have inflection points on both surfaces.

[0020] The third lens L3 is configured using a positive lens whose convex surface faces the image plane side and whose object-side surface has an inflection point at the lens periphery.

[0021] The fourth lens L4 is configured using a negative lens that is concave on the image side and has an inflection point in the periphery.

[0022] The first lens L1 to the fourth lens L4 configured in this manner are all aspherical lenses, each characterized by its aspherical shape. Furthermore, by making the first lens L1 and the fourth lens L4 shaped to have an inflection point, it is possible to highly correct aberrations while keeping the thickness (total length) of the imaging lens 100 in the light direction thin.

[0023] As for the material of the lens, optical plastic material or glass material can be used, as will be shown in the examples described later.

[0024] 2A to 2C, 4A to 4C, 6A to 6C, 8A to 8C, 10A to 10C, 12A to 12C, 14A to 14C, 16A to 16C, 18A to 18C, and 20A to 20C respectively show longitudinal aberration diagrams, MTF diagrams, and distortion grating diagrams for imaging lens 100 according to the first to tenth embodiments. The spherical aberration diagrams show the amount of spherical aberration for the d-line (yellow: wavelength 587.6 nm), g-line (blue: wavelength 435.8 nm), and C-line (red: 653.3 nm). Furthermore, the astigmatism diagrams show the amount of astigmatism at the sagittal image plane, with the solid line S indicating the amount of astigmatism at the tangential image plane, and the dashed line T indicating the amount of astigmatism at the tangential image plane. Furthermore, the distortion diagrams show the amount of distortion at only the d-line. Furthermore, Angle (deg) indicates the imaging half angle of view (°). Regarding MTF, the frequencies are 1 / 4Ny and 1 / 2Ny. At 1 / 4Ny, the five-dotted line indicates the MTF of the sagittal image plane, and the coarse-dashed line indicates the MTF of the tangential image plane. At 1 / 2Ny, the three-dotted line indicates the MTF of the sagittal image plane, and the fine-dashed line indicates the MTF of the tangential image plane. Regarding distortion gratings, the thin line indicates the paraaxial (ideal) grating, and the thick line indicates the actual (actual) grating.

[0025] Next, the conditions for the imaging lens 100 of each embodiment will be described. The imaging lens 100 of each embodiment satisfies the following conditions (1) and (2), where 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. 0.45 < |f / f1| < 0.80 ···(1) 0.25 < |f4 / f1| < 0.50 ···(2)

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

[0027] If f / f1 is equal to or less than the lower limit of condition (1), the overall focal length tends to be shorter, which is advantageous for achieving a wider angle, but astigmatism tends to be excessive and distortion tends to be large, making it difficult to achieve the desired performance. Also, if f / f1 is equal to or greater than 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 because it makes it impossible to achieve the desired performance in the embodiments of the present disclosure. Therefore, by satisfying condition (1), imaging lens 100 can achieve a balance between a short shape (low height) and high performance.

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

[0029] If |f4 / f1| is equal to or less than the lower limit of condition (2), the astigmatism tends to be excessive, and large spherical aberration also occurs, making it difficult to achieve the desired performance. On the other hand, if |f4 / f1| is equal to or greater than the upper limit of condition (2), the spherical aberration tends to be excessive, which disrupts the balance with the astigmatism and makes it difficult to achieve the desired performance.

[0030] That is, when the imaging lens 100 satisfies conditions (1) and (2), it is possible to achieve a good balance between spherical aberration and astigmatism, and to realize a bright, high-performance, and small (compact) imaging lens 100. Here, "small" means reducing the overall length of the imaging lens 100 in the optical axis direction to reduce its thickness, and reducing the aperture of the imaging lens 100.

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

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

[0033] The first lens L1 is a positive lens, and the fourth lens L4 is a negative lens. In the disclosure, in order to balance the chromatic aberration with compactness, the refractive index N1 of the first lens L1 is made of a material having a smaller refractive index than the refractive index N4 of the fourth lens L4, and by satisfying condition (3), the desired favorable chromatic aberration can be achieved.

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

[0035] If the refractive index N1 is equal to or less than the lower limit of condition (4), the optical performance will be further improved, but costs will increase, which is not preferable. On the other hand, if the refractive index N1 is equal to or greater than the upper limit of condition (4), chromatic aberration will be adversely affected, which is not preferable. Therefore, by making the imaging lens 100 satisfy condition (4), a balance between cost and chromatic aberration can be achieved, and an imaging lens 100 that is bright, high-performance, and small (compact) can be realized.

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

[0037] If the refractive index N4 is equal to or smaller than the lower limit of the condition (5), or if the refractive index N4 is equal to or larger than the upper limit of the condition (5), the balance of chromatic aberration is lost. In consideration of the balance between cost and chromatic aberration, satisfying the condition (5) makes it possible to realize a bright, high-performance, and compact imaging lens 100.

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

[0039] Condition (6) is a condition for achieving a balance between the focal length f of the entire optical system and the total length of the OAL.

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

[0041] Furthermore, the imaging lens 100 of each embodiment satisfies the condition (7), where OAL is the total length of the optical system and EfD1 is the effective optical diameter of the lens (first lens L1) arranged closest to the object. 2.9 <OAL / EfD1<3.6 ···(7)

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

[0043] If OAL / EfD1 is equal to or less than the lower limit of condition (7), the optical system will be compact (shortened in the optical axis direction), but it will be difficult to achieve a wide angle of view. If OAL / EfD1 is equal to or greater than the upper limit of condition (7), the performance of the optical system will improve, but it will be difficult to achieve compactness (shortened in the optical axis direction). By satisfying condition (7), imaging lens 100 can achieve compactness (shortened in the optical axis direction) and high performance.

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

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

[0046] If EXP / IH is equal to or less than the lower limit of condition (8), the light incident angle tends to be small, but it tends to be difficult to reduce the overall length of the optical system and thereby achieve compactness. On the other hand, if EXP / IH is equal to or greater than the upper limit of condition (8), the light incident angle tends to be large. Therefore, by satisfying condition (8), imaging lens 100 can be made compact.

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

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

[0049] If |f1 / f2| is below the lower limit of condition (9), the lens power of f2 relative to f1 becomes weak, which tends to result in insufficient correction of spherical aberration and distortion, making it difficult to achieve high performance. Furthermore, if |f1 / f2| is above the upper limit of condition (9), astigmatism tends to become large, which is undesirable. Therefore, imaging lens 100 can achieve high performance by satisfying condition (9).

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

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

[0052] If f3 / f1 is equal to or less than the lower limit of condition (10), astigmatism tends to be excessive, and distortion and coma also occur to a large extent, making it difficult to achieve the desired performance.If f3 / f1 is equal to or greater than the upper limit of condition (10), spherical aberration tends to be excessive, which destroys the balance with astigmatism and makes it difficult to achieve the desired performance.

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

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

[0055] If f3 / f4 is equal to or less than the lower limit of condition (11), astigmatism tends to become excessive and distortion also tends to become large, making it difficult to achieve the desired performance. On the other hand, if f3 / f4 is equal to or greater than the upper limit of condition (11), the overall focal length becomes long and the angle of view tends to narrow. As a result, astigmatism and distortion tend to be improved, but spherical aberration tends to become large, making it difficult to achieve the desired performance. For this reason, imaging lens 100 can achieve a balance between a short shape (low profile) and high performance by satisfying condition (11).

[0056] Furthermore, in the imaging lenses 100 of the first to fifth embodiments, the second lens L2 has negative power, and satisfies condition (16) when the focal length of the second lens L2 is f2 and the focal length of the entire optical system is f. -0.2 < f / f2 < -0.0 (16)

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

[0058] If the f / f2 ratio is below the lower limit of the condition (16), the lens becomes stronger at f2 relative to f, and astigmatism and distortion tend to be undercorrected, making it difficult to achieve high performance. For this reason, imaging lens 100 can achieve high performance by satisfying condition (16).

[0059] In the imaging lenses 100 of the sixth to tenth embodiments, the second lens L2 has positive power and satisfies the condition (16) when the focal length of the second lens L2 is f2 and the focal length of the entire optical system is f. 0.0 < f / f2 < 0.25 (17)

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

[0061] If the f / f2 ratio is equal to or exceeds the upper limit of the condition (17), the lens strength for f2 relative to f becomes too strong, and astigmatism and distortion tend to be undercorrected, making it difficult to achieve high performance. For this reason, imaging lens 100 can achieve high performance by satisfying condition (17).

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

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

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

[0065] Under the control of the control unit 34, the imaging device 31 generates an imaging signal by capturing an image of a predetermined field of view and outputs the imaging signal to the signal processing unit 32. As shown in FIG. 22 , the imaging device 31 includes at least a cover 311, the imaging lens 100 of each embodiment, and a solid-state imaging element 312. The imaging device 31 is disposed on the front side of the information processing device 30. Specifically, the imaging device 31 is disposed in a position where it can capture an image of the user of the information processing device 30. Of course, the position of the imaging device 31 can be changed as appropriate depending on the shape, size, and usage mode of the information processing device 30.

[0066] The cover 311 is configured using a cover glass or the like, which is a member for preventing dirt and dust from being generated on the imaging lens 100. Note that the information processing device 30 may further provide a lid or the like on the cover 311 that opens and closes in response to a user operation.

[0067] The solid-state imaging element 312 receives the image of the object to be imaged formed by the imaging lens 100 and generates an imaging signal by photoelectric conversion. The solid-state imaging element 312 is configured using a CCD sensor, a CMOS sensor, or the like. The solid-state imaging element 312 preferably has 8 million or more effective pixels, so-called 4K or more (3840 x 2160 or more), arranged in a two-dimensional matrix.

[0068] Under the control of the control unit 34, the signal processing unit 32 performs A / D conversion processing and the like on the imaging signal input from the solid-state imaging element 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) or the like.

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

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

[0071] Under the control of the control unit 34, the display unit 35 displays the video being shot that has been image processed by the image processing unit 33, the captured image, the still image corresponding to the image signal stored in the memory unit 36, and various information related to the information processing device 30.

[0072] 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 31. The storage unit 36 is configured using a flash memory, an SSD (Solid State Drive), an HDD (Hard Disk Drive), a memory card, etc.

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

[0074] The input unit 38 receives an operation input from the user 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, and the like.

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

[0076] The information processing device 30 configured in this manner can use the imaging device 31 having the imaging lens 100 to communicate with an external device in high-quality 4K images via web communication via a network.

[0077] In the embodiment, a PC has been described as an example of the information processing device 30, but the imaging device 31 can be applied to imaging devices such as a tablet terminal, a mobile phone, etc. Of course, the imaging device 31 can also be applied to a web camera or the like that can communicate with a PC or the like via wired or wireless communication.

[0078] According to the embodiment described above, it is possible to realize a wide-angle, bright, high-performance, and compact camera.

[0079] Furthermore, according to the embodiment, a half angle of view of approximately 50° can be achieved with four lenses.

[0080] Furthermore, according to the embodiment, the imaging lens 100 can be realized to have a wide angle of view, a small F-number, high performance, and a small size, so that in the case of video shooting, it can accommodate shooting in various environments such as dark environments and high-speed shooting.

[0081] Furthermore, according to the embodiment, it is possible to realize a wide-angle, bright, high-performance, and compact device, thereby improving the matching between the incident angle at the light receiving element of the solid-state imaging element on the image side and the light rays incident on the light receiving surface.

[0082] Furthermore, according to the embodiment, a bright, high-performance, and compact lens with a half angle of view of approximately 50° can be constructed from four lenses, and therefore it can be used as a fixed-focus lens for use in mobile phones such as smartphones and PCs, for example. Therefore, when high-pixel video recording of 4K or more (3840 x 2160 or more) is required, sufficient aberration correction can be performed compared to conventional imaging lenses, and the required performance can be met.

[0083] Furthermore, according to the embodiment, a bright, high-performance, and compact lens with a half angle of view of approximately 50° can be configured using four lenses, which shortens the overall length of imaging lens 100 in the optical axis direction and reduces the lens diameter, thereby achieving a compact size. This reduces the refractive power of the compact lens and reduces the effects of manufacturing errors and assembly errors. As a result, productivity is improved and production costs can be reduced.

[0084] Various inventions can be formed by appropriately combining multiple components disclosed in the information processing device according to the embodiment of the present disclosure. For example, some components may be deleted from all of the components described in the information processing device according to the embodiment of the present disclosure. Furthermore, the components described in the information processing device according to the embodiment of the present disclosure may be appropriately combined.

[0085] Furthermore, in the information processing device according to the embodiment of the present disclosure, the above-described "unit" can be read as "means" or "circuit," etc. For example, a control unit can be read as control means or a control circuit.

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

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

[0088] Examples 1 to 10 of the imaging lens 100 corresponding to the first to tenth embodiments, respectively, 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 (F number) R: Radius of curvature of the surface D: Surface spacing Nd: Refractive index for the d line Vd: Abbe number for the d line SD: Effective radius An aspherical surface can be expressed by the well-known formula (15) below using aspherical coefficients, where X is the depth in the optical axis direction, H is the height from the optical axis, R is the paraxial radius of curvature, k is the conic constant, and CN is a high-order aspherical coefficient (N=4 or an even number). X=(H 2 / R) / [1+{1-k(H / r) 2} 1 / 2 ] +Σ N=4:even CNH N ···(15) Here, Σ N≧4:even means the sum for N being an even number greater than or equal to 4.

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

[0090] [Table 1]

[0091] The aspheric data is shown below. [Table 2] In the above notation of aspherical surfaces, for example, "2.1143.E-02" means "2.1143*10-2." This also applies to the other examples below.

[0092] The parameter values for each condition are as follows: Table 3 also lists EP: entrance pupil position. [Table 3]

[0093] In addition to conditional expressions (1) to (11) and (16), this table also lists (12) to (14) for reference. [Table 4] The meanings of the conditions (12) to (14) are as follows: 0.01 < |f4 / f2|<0.15 ···(12) Regarding conditional expression (12), f2 represents the focal length of the second lens L2, and f4 represents the focal length of the fourth lens L4, and this condition is for the balance between the focal lengths of the second lens L2 and the fourth lens L4. High performance can be achieved within the range of conditional expression (12). If the value is below the lower limit of conditional expression (12), astigmatism becomes large, and if the value is above the upper limit of conditional expression (12), spherical aberration becomes large. Therefore, it is desirable to satisfy the range of conditional expression. 0.01 < |f3 / f2|< 0.17 ···(13) Regarding conditional expression (13), f2 represents the focal length of the second lens L2, f3 represents the focal length of the third lens L3, and is a condition for the balance between the focal lengths of the second lens L2 and the third lens L3. High performance can be achieved within the range of conditional expression (13). If the value is below the lower limit of conditional expression (13), astigmatism becomes large, and if the value is above the upper limit of conditional expression (13), spherical aberration becomes large, so it is preferable to satisfy the range of conditional expression (13). The present disclosure is characterized in that the power of the second lens L2 is weaker than the power of the other lenses, but by arranging a positive or negative lens with a relatively weaker power than the other lenses in the second lens L2, the present disclosure can effectively correct astigmatism, spherical aberration, and distortion. 0.61 < OAL / 2*IH < 0.65 ···(14) In conditional expression (14), OAL represents the total optical length, IH represents the image height, or the image circle of the optical system, and indicates the ratio of the total optical length to the image circle. As conditional expression (14) indicates, the total optical length relative to the image circle is 0.61 to 0.65, and it is clear that imaging lens 100 of the present disclosure is low in height. Furthermore, these conditional expressions (12) to (14) are also applied to the second and subsequent examples.

[0094] In each example, the first lens L1 to the fourth lens L4 have aspherical surfaces, and the aspherical surfaces effectively correct aberrations.

[0095] The aberration diagrams, MTF, and distortion grating for Example 1 are shown in FIGS. 2A to 2C, and as is clear from each diagram, the performance is excellent.

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

[0097] [Table 5]

[0098] The aspheric data is shown below. [Table 6]

[0099] The parameter values for each condition are as follows: [Table 7] [Table 8]

[0100] The aberration diagrams, MTF, and distortion gratings are shown in FIGS. 4A to 4C, and as is clear from each diagram, the performance is excellent.

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

[0102] [Table 9]

[0103] The aspheric data is shown below. [Table 10]

[0104] The parameter values for each condition are as follows: [Table 11]

[0105] [Table 12]

[0106] The aberration diagrams, MTF, and distortion gratings are shown in FIGS. 6A to 6C, and as is clear from each diagram, the performance is excellent.

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

[0108] The aspheric data is shown below. [Table 14]

[0109] The parameter values for each condition are as follows: [Table 15]

[0110] [Table 16]

[0111] The aberration diagrams, MTF, and distortion gratings are shown in FIGS. 8A to 8C, and as is clear from each aberration diagram, the performance is excellent.

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

[0113] The aspheric data is shown below. [Table 18]

[0114] The parameter values for each condition are as follows: [Table 19]

[0115] [Table 20]

[0116] The aberration diagrams, MTF, and distortion gratings are shown in FIGS. 10A to 10C, and as is clear from each aberration diagram, the performance is excellent.

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

[0118] The aspheric data is shown below. [Table 22]

[0119] The parameter values for each condition are as follows: [Table 23]

[0120] [Table 24]

[0121] The aberration diagrams, MTF, and distortion gratings are shown in FIGS. 12A to 12C, and as is clear from each aberration diagram, the performance is excellent.

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

[0123] The aspheric data is shown below. [Table 26]

[0124] The parameter values for each condition are as follows: [Table 27]

[0125] [Table 28]

[0126] The aberration diagrams, MTF, and distortion gratings are shown in FIGS. 14A to 14C, and as is clear from each aberration diagram, the performance is excellent.

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

[0128] The aspheric data is shown below. [Table 30]

[0129] The parameter values for each condition are as follows: [Table 31]

[0130] [Table 32]

[0131] The aberration diagrams, MTF, and distortion gratings are shown in FIGS. 16A to 16C, and as is clear from each aberration diagram, the performance is excellent.

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

[0133] The aspheric data is shown below. [Table 34]

[0134] The parameter values for each condition are as follows: [Table 35]

[0135] [Table 36]

[0136] The aberration diagrams, MTF, and distortion gratings are shown in FIGS. 18A to 18C, and as is clear from each aberration diagram, the performance is excellent.

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

[0138] The aspheric data is shown below. [Table 38]

[0139] The parameter values for each condition are as follows: [Table 39]

[0140] [Table 40]

[0141] The aberration diagrams, MTF, and distortion gratings are shown in FIGS. 20A to 20C, and as is clear from each aberration diagram, the performance is excellent.

[0142] As described above, as shown in Examples 1 to 10 and Figures 2A to 2C, 4A to 4C, 6A to 6C, 8A to 8C, 10A to 10C, 12A to 12C, 14A to 14C, 16A to 16C, 18A to 18C, and 20A to 20C, the imaging lens 100 of the present disclosure is bright, has high performance, and is compact (shortened in the optical axis direction), and achieves a half angle of view of approximately 50° with a four-lens configuration, and is clearly suitable as an imaging device, particularly an imaging device for laptop PCs.

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

[0144] 30 Information processing equipment 31 Imaging device 100 Imaging Lens L1 First lens L2 Second lens L3 Third lens L4 4th lens S aperture stop CG cover glass

Claims

1. a first lens to a fourth lens arranged in order from the object side; The aperture stop closest to the object, It consists of The first lens is It is a positive meniscus lens with the convex surface facing the object side. The second lens is A lens having an inflection point on at least one surface and a small thickness deviation ratio, The third lens is A positive lens with a convex surface facing the image plane and an inflection point on at least one surface in the lens periphery, The fourth lens is A negative lens that is concave on the image side and has an inflection point in the peripheral portion on the image side, When the focal length of the first lens is f1, the focal length of the fourth lens is f4, the focal length of the entire optical system is f, the refractive index of the material of the fourth lens with respect to the d-line is N4, the total optical length is OAL, and the image height is IH, the conditions (1), (2), (5), and (14) are satisfied. 0.45 < | f / f1 | < 0.80 ... (1) 0.25 < | f4 / f1 | < 0.50 ... (2) 1.63 < N4 < 1.67...(5) 0.61 < OAL / 2*IH < 0.65 (14) An imaging lens that satisfies the above.

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 and the refractive index of the material of the fourth lens with respect to the d-line is N4, the condition (3) is satisfied. N1 < N4...(3) An imaging lens that satisfies the above.

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, the condition (4) is satisfied. 1.49 < N1 < 1.55 (4) An imaging lens that satisfies the above.

4. The imaging lens according to claim 1 , When the focal length of the entire optical system is f and the total length of the optical system is OAL, the condition (6) is satisfied. 0.60<f / OAL<0.75...(6) An imaging lens that satisfies the above.

5. The imaging lens according to claim 1 , When the total optical length is OAL and the optical effective diameter of the lens closest to the object side is EfD1, the condition (7) is satisfied. 2.9 < OAL / EfD1 < 3.6 ... (7) An imaging lens that satisfies the above.

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

7. 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) is satisfied. 0.01 < | f1 / f2 | < 0.40 ... (9) An imaging lens that satisfies the above.

8. 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) is satisfied. 0.25 < f3 / f1 < 0.55 (10) An imaging lens that satisfies the above.

9. 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) is satisfied. 0.7 < | f3 / f4 | < 1.3 ... (11) An imaging lens that satisfies the above.

10. The imaging lens according to claim 1 , The second lens is When the second lens has negative power, the focal length of the second lens is f2, and the focal length of the entire optical system is f, the condition (16) is satisfied. -0.2 < f / f2 < -0.0 (16) An imaging lens that satisfies the above.

11. The imaging lens according to claim 1 , The second lens is When the second lens has a positive power, the focal length of the second lens is f2, and the focal length of the entire optical system is f, the condition (17) is satisfied. 0.0 < f / f2 < 0.25 (17) An imaging lens that satisfies the above.

12. The imaging lens according to claim 1 ; a solid-state image sensor that receives an image formed by the imaging lens and generates an imaging signal; Equipped with Imaging device.

13. The imaging device according to claim 12; a display unit that displays an image corresponding to the imaging signal generated by the imaging device; Equipped with Information processing device.

Images