Image capturing device and detection system having the same

Abstract

To provide an image capturing device which is compact and is equipped with an optical system that offers high optical performance even when not directly facing an object.SOLUTION: An image capturing device provided herein comprises an optical system including a first substrate and optical elements with refractive power arranged on the first substrate, and a light reception element having a light receiving surface configured to allow an image to be formed by the optical system. A distance from an optical axis of the optical system to the center of the light receiving surface, and a distance from the center of the light receiving surface to a point furthest from the center on the light receiving surface are each set appropriately.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an imaging device and a detection system having the same. [Background technology]

[0002] Conventionally, optical systems that are small in size and have high optical performance have been proposed for use in imaging devices that perform gaze detection, iris authentication, live body detection, and the like (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 9,798,115 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional imaging devices, when the subject and the optical system are not directly facing each other, distortion and partial blurring of the image occurs. Although imaging devices that incorporate a half mirror in the eyepiece optical system so that the subject and the optical system are directly facing each other and detect the line of sight have been proposed, the half mirror occupies a large space, which results in an increase in the size of the imaging device.

[0005] An object of the present invention is to provide an imaging device that is small and includes an optical system that has high optical performance even when not directly facing a subject. [Means for solving the problem]

[0006] An imaging device according to one aspect of the present invention includes an optical system including a first substrate and an optical element having refractive power disposed on the first substrate, and a light receiving element having a light receiving surface on which an image is formed by the optical system, wherein s is the distance from the optical axis of the optical system to the center of the light receiving surface, and Rimmax is the distance from the farthest position from the center on the light receiving surface to the center, 0.2≦s / Rimmax≦1.1 The present invention is characterized in that the following conditional expression is satisfied: Effect of the Invention

[0007] According to the present invention, it is possible to provide an imaging device that is small and includes an optical system that has high optical performance even when not directly facing a subject. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a cross-sectional view of the optical system of the first embodiment. [Diagram 2] 4A to 4C are aberration diagrams of the optical system of Example 1. [Diagram 3] FIG. 11 is a cross-sectional view of an optical system according to a second embodiment. [Figure 4] 11A to 11C are aberration diagrams of the optical system of Example 2. [Diagram 5] FIG. 11 is a cross-sectional view of an optical system according to a third embodiment. [Figure 6] 11A to 11C are aberration diagrams of the optical system of Example 3. [Figure 7] FIG. 11 is a cross-sectional view of an optical system according to a fourth embodiment. [Figure 8] 11A to 11C are aberration diagrams of the optical system of Example 4. [Figure 9] FIG. 11 is a cross-sectional view of an optical system according to a fifth embodiment. [Figure 10] 13A to 13C are aberration diagrams of the optical system of Example 5. [Figure 11] 2 is a diagram showing a light receiving surface of the imaging device according to the first embodiment as viewed from a direction perpendicular to the optical axis. [Figure 12] 11 is a diagram showing a light receiving surface of an imaging device according to a second embodiment, viewed from a direction perpendicular to the optical axis. [Figure 13] 11 is a diagram showing a light receiving surface of an imaging device according to a third embodiment, viewed from a direction perpendicular to the optical axis. [Figure 14] 13 is a diagram showing a light receiving surface viewed from a direction perpendicular to the optical axis in the imaging device of the fourth embodiment. [Figure 15] 13 is a diagram showing a light receiving surface viewed from a direction perpendicular to the optical axis in the imaging device of the fifth embodiment. FIG. [Figure 16] FIG. 13 is a schematic diagram of an electronic device according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to refer to the same components, and duplicated descriptions will be omitted.

[0010] The imaging device of each embodiment has an optical system (imaging optical system) IO and a light receiving element having a light receiving surface on which an image is formed by the optical system IO.

[0011] The optical system IO in each embodiment is a small optical system obtained by using a technology called wafer level optics. Such an optical system is called a wafer level lens, and an imaging device using a wafer level lens as an imaging optical system is called a wafer level camera. The optical system IO in each embodiment is used as an imaging optical system used in a built-in camera of electronic devices such as a mobile phone, a smartphone, a wearable terminal, and an HMD (head mounted display), or as an objective optical system of an endoscope. The optical system IO in each embodiment is preferably used together with a main optical system such as an eyepiece optical system of the above-mentioned electronic device, and is used in a state where it cannot be directly faced to a subject.

[0012] 1, 3, 5, 7, and 9 are cross-sectional views of the optical systems (wafer level lens / wafer level optics (WLO)) IO of Examples 1 to 5, respectively. In each cross-sectional view, the left side is the object side (front) and the right side is the image side (rear).

[0013] OB is an object plane (subject plane). IP is an image plane. An imaging surface of an imaging element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor in an imaging device may be disposed on the image plane IP. A photosensitive surface equivalent to the film surface of a silver halide film camera may also be disposed on the image plane IP. However, as long as light rays are incident within the effective area of ​​a light receiving element such as an imaging element or a photosensitive element, it is not necessary for the light rays to be incident on the entire surface of the image plane IP.

[0014] The optical system IO in each embodiment includes a substrate (first substrate) and an optical element having a refractive power arranged on the substrate. The optical system IO in each embodiment includes substrates SB1 and SB2 arranged in this order from the object side to the image side. A glass substrate GSB for protecting the light receiving surface is arranged between the substrate SB2 and the image surface IP. However, a back cover glass may be used instead of the glass substrate GSB.

[0015] The glass substrate GSB may also be made by bonding two flat plates together. This allows the optical system and the imaging section to be produced separately, and the imaging device to be efficiently manufactured by bonding the glass flat surfaces together. In addition, the relative positions of the optical system and the imaging section can be changed, making it easy to prepare imaging devices with various specifications.

[0016] In each embodiment, in order to miniaturize the optical system IO, each lens is manufactured by a wafer-level process. That is, the lenses are manufactured by forming a lens layer made of a curable resin material or the like on a wafer that becomes the substrates SB1 and SB2. The substrate and the light receiving element manufactured by the wafer-level process are arranged at a predetermined interval, bonded outside the effective area, and then cut, so that a large number of wafer-level lenses can be manufactured at once.

[0017] As materials for forming the lens layer, thermoplastic resins, ultraviolet curing resins, and thermosetting resins are used. For example, there are acrylic resins, modified acrylic resins, polycarbonate resins, modified polycarbonate resins (such as those containing a fluorene skeleton or Iupizeta manufactured by Mitsubishi Gas Chemical Co., Ltd.), silicone resins, cycloolefin polymers, and cycloolefin copolymers. In addition, there are polyvinylcarbazole, polystyrene, polyethylene, Teflon (registered trademark), Teflon AF manufactured by Mitsui-Chemours Fluoro Products Co., Ltd., Cytop manufactured by AGC Inc., and perfluoroalkoxyalkane. In addition, a blend, copolymer, or a further blend of the copolymers of some of these may be used. In addition, a material in which particles or crystals of organic low molecular weight or inorganic materials are added and / or kneaded to these resin materials may be used. By using such resin materials, an optical element having a refractive index can be easily formed. In the optical system IO of each embodiment, it is preferable to use glass, quartz, inorganic crystals, transparent ceramics, and engineering plastics as the material of the substrate. In each embodiment, the substrates SB1 and SB2 are made of glass, but the present invention is not limited to this.

[0018] 2, 4, 6, 8, and 10 are aberration diagrams of the optical system IO of Examples 1 to 5, respectively. Each aberration diagram is a spherical aberration diagram, an astigmatism diagram, a distortion aberration diagram, and a lateral aberration diagram. In the spherical aberration diagram, Fno is the F-number, and shows the amount of spherical aberration for a wavelength of 850 nm or a wavelength of 950 nm. In the astigmatism diagram, S shows the amount of astigmatism in the sagittal image plane, and M shows the amount of astigmatism in the meridional image plane. In the distortion aberration diagram, the amount of distortion aberration for a wavelength of 850 nm or a wavelength of 950 nm is shown. In the astigmatism and distortion aberration, the direction horizontal to the optical axis OA, the direction perpendicular to the optical axis OA, and the diagonal direction of the light receiving element are plotted in order of image height on the light receiving element, and the between them is spline interpolated. In the lateral aberration diagram, the solid line indicates the meridional lateral aberration, and the dashed line indicates the sagittal lateral aberration. ω is the imaging half angle of view (°). When there is only one lens with refractive power in the optical system IO, the optical axis OA is defined as the axis of rotation. When there are two or more such lenses, the optical axis OA is defined as the sum of the unit vectors in the directions of the axes of rotation (both defined as directions from the object side to the image side).

[0019] 11, 12, 13, 14, and 15 are views of the light receiving surface viewed from a direction perpendicular to the optical axis OA in the imaging devices of Examples 1 to 5, respectively. In each example, the optical system IO is disposed so that the optical axis OA does not coincide with the center C of the light receiving surface. That is, the optical axis OA of the optical system IO is tilted with respect to the optical axis of the main optical system whose optical axis coincides with the center of the light receiving surface on the light receiving surface. Also, on the light receiving surface, the center of the effective area contributing to imaging and image acquisition does not coincide with the center C of the light receiving surface.

[0020] The characteristic configuration of the optical system IO in each embodiment will be described below.

[0021] The optical system IO of each embodiment satisfies the following conditional expression (1).

[0022] 0.2≦s / Rimmax≦1.1 (1) Here, s is the distance from the optical axis OA to the center C of the light receiving surface. Rimmax is the distance from the farthest position from the center C on the light receiving surface to the center C.

[0023] For example, when the shape of the light-receiving surface is a rectangle or a square, the distance Rimmax is the distance from the center C of the light-receiving surface to the vertex. Furthermore, the center C of the light-receiving surface and the position farthest from the center C of the light-receiving surface are considered to be within the effective area that contributes to the image formation of the light-receiving surface. There are no limitations on the direction from the optical axis OA to the position of the center C of the light-receiving surface, and it can be, for example, the long side direction, short side direction, diagonal direction, etc. of the light-receiving surface.

[0024] In a general coaxial optical system, the optical system and the subject cannot face each other directly, and for example, when the subject looks up or down at an angle, keystone distortion or one-sided blur occurs. By separating the center of the light receiving surface C from the optical axis OA within the range of conditional formula (1), the center of the imaging range can be offset from the optical axis OA. This makes it possible to provide an imaging device suitable for gaze detection in a camera finder or HMD or live body detection in a wearable device, where the optical system IO cannot be faced directly to the subject. For example, in the eyepiece of a camera finder or HMD, the eyepiece optical system is arranged at a position facing the user's eyes, so it is difficult to face the camera for gaze detection directly to the subject (the user's eyes and the light reflected by the eyes). The optical system IO of each embodiment is preferably used under such conditions.

[0025] If the lower limit of conditional formula (1) is exceeded, the offset of the imaging range caused by separating the center C of the light receiving surface from the optical axis OA becomes small, and in order to obtain high image quality, it is necessary to make the optical system IO and the subject face each other almost directly, which is undesirable. If the upper limit of conditional formula (1) is exceeded, the optical system IO and the light receiving element are separated significantly, which increases the size of the imaging device, which is undesirable for applications where there is a strong need for miniaturization, such as HMDs and wearable devices.

[0026] Normally, when using a CMOS sensor or a CCD sensor, space is required to arrange wiring and circuits, which leads to an increase in the size of the imaging device. In the imaging device of each embodiment, the wiring and circuit of the light receiving element can be arranged on the opposite side of the center C of the light receiving surface with respect to the optical axis OA. Therefore, the wiring and circuit can be arranged in the shadow of the lens, and the imaging device can be made smaller.

[0027] It is preferable that the numerical range of conditional expression (1) be the numerical range of the following conditional expression (1a).

[0028] 0.2≦s / Rimmax≦0.9 (1a) It is further preferable that the numerical range of conditional formula (1) be the numerical range of the following conditional formula (1b).

[0029] 0.25≦s / Rimmax≦0.70 (1b) With the above configuration, it is possible to realize an imaging device that is small and includes an optical system that has high optical performance even when not directly facing the subject.

[0030] Next, a description will be given of configurations that are preferably satisfied in the optical system IO of each embodiment.

[0031] It is preferable that a lens (first optical element) L12 with negative refractive power is formed on the image side of the substrate SB1, and a lens (second optical element) L2 with positive refractive power is formed on the image side of the substrate SB2. These lenses are formed by a wafer-level process. This configuration is preferable because it can ensure imaging performance over a wide angle of view and can ease the angle of incidence on the light receiving surface. It is more preferable that these lenses are aspheric lenses.

[0032] On the object side of the substrate SB1, it is preferable that an aspheric lens (third optical element) L11 with a positive refractive power is formed at the end of the effective area contributing to image formation. By arranging the aspheric surface at a position where the separation of the axial and off-axial rays is large, it is preferable because off-axis aberration can be corrected well. By making the refractive power of the end positive, it is possible to make the surface close to concentric for the rays passing through the end, which is preferable because it is possible to improve the image quality at the end of the screen. In the optical system IO of each embodiment, since the optical axis OA does not coincide with the center C of the light receiving element, a wider one-sided angle of view is required compared to an optical system in which the optical axis coincides with the center of the light receiving element. For this reason, correction of off-axis aberration is more important than in a general optical system.

[0033] The substrate does not necessarily have to be made up of one substrate, and may be made up of two or more substrates. In particular, when the substrate SB1 is made up of two substrates, the optical performance can be improved by forming the lenses L11 and L12 on different substrates and bonding the two substrates together.

[0034] In addition, for the purpose of protecting the lens, a flat plate or a protective plate with approximately equal curvature on both sides may be disposed on the object side. The flat plate or protective plate may be used as a wavelength selection filter, or a wavelength selection filter may be formed on a substrate.

[0035] In addition, in a configuration in which the lens is formed closest to the object, it is preferable to use a resin material for the lens, so surface durability can be an issue when the lens is exposed to the outside world. However, in consumer products such as HMDs, a cover member is generally used to ensure the appearance quality, so placing the lens closest to the object does not necessarily pose a big issue.

[0036] It is preferable that an aperture stop is formed on the substrate SB2. For example, the aperture stop can be formed on the substrate SB2 by depositing a light-shielding film such as chromium using a mask, and then etching the film after deposition. Generally, the aperture stop refers to a stop whose diameter is variable, but in this specification, it also includes a stop whose diameter is not variable. The aperture stop may be formed by sandwiching a thin sheet or the like having an aperture shape. In addition, the shape of the aperture is not limited to a circle, and may be a rectangle or a rounded rectangle whose four corners are fan-shaped. Forming the aperture stop on the substrate SB, i.e., on a flat surface, is preferable in terms of manufacturing because it makes it easier to control the mask arrangement in the thickness direction.

[0037] In addition, it is preferable that the lens surfaces of the lenses L12 and L2 have a rotationally symmetrical shape. This simplifies inspection during manufacturing. The outer periphery of the lens may have a square or rectangular shape.

[0038] Next, the conditions that the optical system IO of each embodiment preferably satisfies will be described. The optical system IO of each embodiment preferably has a plane that is a boundary with the air and is provided on an element made of glass or resin within an effective area that contributes to image formation, and preferably satisfies the following conditional formula (2).

[0039] 0.5≦θ≦20.0 (2) Here, θ is the angle [°] of the above-mentioned plane with respect to the optical axis OA. Note that the plane includes the lens surface, both sides of the flat plate, and their bonding surfaces.

[0040] By satisfying conditional expression (2), it becomes possible to tilt the object plane OB. This allows the object plane OB to coincide with the object plane even in cases where the optical system looks at an oblique object that is not directly facing the optical system IO. If the lower limit of conditional expression (2) is exceeded, the effect of tilting the object plane OB becomes small, which is undesirable. If the upper limit of conditional expression (2) is exceeded, the tilt of the object plane OB becomes too large, which makes manufacturing difficult, which is undesirable. In addition, a large space is required to place the tilted surface, which increases the size of the optical system IO, which is undesirable.

[0041] It is preferable that the optical system IO in each embodiment satisfies one or more of the following conditional expressions (3) to (10).

[0042] 0.9≦Φ2i / Φ≦1.5 (3) 0.0≦|Φ1o / Φ|≦0.4 (4) -1.6≦Φ1i / Φ≦-0.2 (5) -1.9≦Φ1i / Φ2i≦-0.1 (6) 0.1≦d12 / f≦2.0 (7) 35<ω<150 (8) 0 <f≦10 (9) 0.02≦f / id≦1.00 (10) Here, Φ is the refractive power of the optical system IO. Φ1o is the refractive power of the lens L11 formed on the object side of the substrate SB1. Φ1i is the refractive power of the lens L12 formed on the image side of the substrate SB1. Φ2i is the refractive power of the lens L2 formed on the image side of the substrate SB2. ω is the angle of view [°] in the direction connecting the center C of the light receiving surface and the center of the optical axis OA. d12 is the distance on the optical axis from the image side surface of the lens L12 to the image side surface of the substrate SB2. f is the focal length of the optical system IO. id is the distance from the surface of the optical system IO closest to the object to be recognized / detected.

[0043] The optical system IO in each embodiment has an inverted telephoto configuration. This configuration allows for good correction of aberrations over a wide range of angles of view. This configuration is also effective for widening the angle of view of a coaxial system. In addition, the optical system IO in which the optical axis OA and the center C of the light receiving surface are spaced apart is preferable because the angle of view on one side of the center C of the light receiving surface and the optical axis OA is larger (compared to a coaxial system with the same angle of view).

[0044] If the lower limit of conditional formula (3) is exceeded, the angle of incidence on the light receiving surface becomes large, which undesirably leads to increased crosstalk between pixels, etc. If the upper limit of conditional formula (3) is exceeded, the positive and negative refractive powers constituting the inverted telephoto type become too large, which undesirably leads to an excessively long overall length.

[0045] By definition, the lower limit of conditional expression (4) cannot be exceeded. If the upper limit of conditional expression (4) is exceeded, the refractive power of lens L11, which is disposed closest to the object and is therefore susceptible to the effects of temperature changes, becomes too large, resulting in significant changes in image quality and focal position due to temperature changes, which is undesirable.

[0046] If the lower limit of conditional expression (5) is exceeded, the angle of incidence on the light receiving surface becomes large, which is undesirable. In addition, the diameter of lens L12 becomes large, which is undesirable. When manufacturing the optical system IO of each embodiment, the surface interval is adjusted by inserting a spacer between the substrates SB1 and SB2. At this time, the wider the outer effective area of ​​lens L12 and the outer effective area of ​​the lens formed on the object side of substrate SB2, the wider the area in which the spacer can be arranged, and the more accurate the surface interval can be maintained. For this reason, it is preferable that the diameter of lens L12 is not too large. If the upper limit of conditional expression (5) is exceeded, the positive and negative refractive powers constituting the inverted telephoto type become too large, and the total length becomes too long, which is undesirable.

[0047] If the lower limit of conditional expression (6) is exceeded, the positive refractive power constituting the inverted telephoto type becomes too strong, and the angle of incidence on lens L2 becomes large. This makes it difficult to correct off-axis aberrations, which is undesirable. If the upper limit of conditional expression (6) is exceeded, the negative refractive power constituting the inverted telephoto type becomes too strong, and the diameter of the effective area of ​​lens L2 becomes larger than the surface of lens L2. This makes it more difficult to mold lens L2, which is undesirable.

[0048] If the lower limit of conditional expression (7) is exceeded, the distance between the lenses with positive and negative refractive powers that make up the inverted telephoto type becomes small, resulting in a state close to a single lens. This is undesirable because it makes it difficult to correct aberrations over a wide angle of view range that has been achieved with the inverted telephoto type configuration. If the upper limit of conditional expression (7) is exceeded, light diverging from the lens on substrate SB1 travels a long optical path before reaching substrate SB2. This causes the diameter of the effective area of ​​the lens on substrate SB2 to become large, making it more difficult to mold, which is undesirable.

[0049] If the lower limit of conditional expression (8) is exceeded, the angle of view becomes narrow, and the subject often goes out of frame due to an error in the installation position of the imaging device or the movement or displacement of the subject. Such an imaging device is not suitable for devices such as HMDs and wearable devices. If the upper limit of conditional expression (8) is exceeded, the angle of view becomes too wide, making it difficult to satisfactorily correct off-axis aberrations, which is not preferable.

[0050] Since the optical system IO of each embodiment is fabricated using a wafer-level process, by satisfying conditional formula (9), the number of optical systems IO that can be obtained from one wafer increases, and many optical systems IO can be manufactured at one time. Since the optical system IO of each embodiment is an imaging lens for primary image formation and has positive refractive power, it does not fall below the lower limit of conditional formula (9). If the upper limit of conditional formula (9) is exceeded, the optical system IO will become large, which is not preferable.

[0051] If the lower limit of conditional expression (10) is exceeded, the image magnification will be reduced, and the effect of offsetting the image plane or introducing an inclined surface into the optical system IO will be reduced, which is undesirable. If the upper limit of conditional expression (10) is exceeded, the distance to the object will be very close, making it difficult to illuminate the object, which is undesirable. In addition, if the object is blurred or displaced, the image will move significantly, making it difficult to capture the desired area, which is undesirable.

[0052] It is preferable that the numerical ranges of the conditional expressions (2) to (10) be the numerical ranges of the following conditional expressions (2a) to (10a).

[0053] 0.5≦θ≦18.0 (2a) 0.9≦Φ2i / Φ≦1.4 (3a) 0.00≦|Φ1o / Φ|≦0.32 (4a) -1.55≦Φ1i / Φ≦-0.25 (5a) -1.70≦Φ1i / Φ2i≦-0.15 (6a) 0.2≦d12 / f≦1.4 (7a) 35<ω<100 (8a) 0 <f≦7 (9a) 0.025≦f / id≦0.095 (10a) It is further preferable that the numerical ranges of the conditional expressions (2) to (10) be the numerical ranges of the following conditional expressions (2b) to (10b).

[0054] 0.5≦θ≦13.0 (2b) 0.93≦Φ2i / Φ≦1.35 (3b) 0.00≦|Φ1o / Φ|≦0.25 (4b) -1.5≦Φ1i / Φ≦-0.3 (5b) -1.5≦Φ1i / Φ2i≦-0.2 (6b) 0.3≦d12 / f≦1.1 (7b) 35<ω<70 (8b) 0 <f≦3 (9b) 0.035≦f / id≦0.085 (10b) The optical system of each of the embodiments IO will be described in detail below. EXAMPLES

[0055] 1, in this embodiment, the object plane OB is inclined by 25° with respect to a plane perpendicular to the optical axis OA. In other words, if the object is flat, a flat image plane can be obtained for the object even if the optical system IO is arranged with an inclination of 25°.

[0056] The optical system IO of this embodiment is designed to focus on an object located 25 mm away from the surface closest to the object.

[0057] FIG. 2 is an aberration diagram for a wavelength of 850 nm when focused at an object distance of 25 mm. The object distance is the distance from the lens surface of lens L11 on the object side, and this is the same for other embodiments. The aberration diagram in FIG. 2 is for a wavelength of 850 nm, but the optical system IO can also be used in the visible range. In this case, the object distance becomes slightly shorter due to the wavelength dispersion of the refractive index. If it is desired to set the object distance to 25 mm, it is necessary to adjust the distance between the light receiving surface and the substrate SB2 to be shorter.

[0058] 11, the size of the effective area of ​​the light receiving surface is 1.44 mm × 1.92 mm, and the center C of the light receiving surface is separated from the optical axis OA by 0.36 mm. The optical system IO of this embodiment may be used as a coaxial system in combination with a light receiving element having an effective area of ​​2.16 mm × 1.96 mm, for example. EXAMPLES

[0059] As shown in FIG. 3, in this embodiment, the object plane OB is horizontal to a plane perpendicular to the optical axis OA.

[0060] The optical system IO of this embodiment is designed to focus on an object located 25 mm away from the surface closest to the object.

[0061] FIG. 4 shows an aberration diagram for a wavelength of 850 nm when focused at an object distance of 25 mm.

[0062] 12, the size of the effective area of ​​the light receiving surface is 1.44 mm × 1.96 mm, and the center C of the light receiving surface is separated from the optical axis OA by 0.72 mm. The optical system IO of this embodiment may be used as a coaxial system in combination with a light receiving element having an effective area of ​​2.88 mm × 1.96 mm, for example. EXAMPLES

[0063] 5, in this embodiment, the object surface OB is inclined by 25° with respect to a plane perpendicular to the optical axis OA. Also, the eighth surface counting from the object side (surface No. 8) is inclined by 10°.

[0064] The optical system IO of this embodiment is designed to focus on an object located 25 mm away from the surface closest to the object.

[0065] FIG. 6 is an aberration diagram for a wavelength of 950 nm when the lens is focused at an object distance of 25 mm in this embodiment.

[0066] In FIG. 13, the size of the effective area of ​​the light receiving surface is 1.41 mm×1.41 mm, and the center C of the light receiving surface is 0.5 mm away from the optical axis.

[0067] Furthermore, the optical system of the imaging apparatus of this embodiment may be used as a coaxial system in combination with a light receiving element having an effective area of, for example, 2.12 mm×2.12 mm. EXAMPLES

[0068] As shown in FIG. 7, in this embodiment, the object plane OB is inclined at 45° with respect to a plane perpendicular to the optical axis OA.

[0069] The optical system IO of this embodiment is designed to focus on an object located 25 mm away from the surface closest to the object.

[0070] FIG. 8 is an aberration diagram for a wavelength of 950 nm when the object distance in this embodiment is focused at 25 mm.

[0071] 14, the size of the effective area of ​​the light receiving surface is 1.44 mm × 1.92 mm, and the center C of the light receiving surface is spaced 0.72 mm from the optical axis. The optical system IO of this embodiment may be used as a coaxial system in combination with a light receiving element having an effective area of ​​2.16 mm × 1.96 mm. EXAMPLES

[0072] 9, in this embodiment, the object surface OB is inclined by 25° with respect to a plane perpendicular to the optical axis OA. Also, the eighth surface counting from the object side (surface No. 8) is inclined by 10°.

[0073] The optical system IO of this embodiment is designed to focus on an object located 25 mm away from the surface closest to the object.

[0074] FIG. 10 is an aberration diagram for a wavelength of 950 nm when the present embodiment is focused at an object distance of 25 mm.

[0075] 15, the size of the effective area of ​​the light receiving surface is 1.44 mm × 1.92 mm, and the center C of the light receiving surface is separated from the optical axis OA by 0.72 mm. The optical system IO of this embodiment may be used as a coaxial system in combination with a light receiving element having an effective area of ​​2.16 mm × 1.96 mm, for example.

[0076] Numerical examples 1 to 5 corresponding to the first to fifth embodiments, respectively, are given below.

[0077] In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial spacing (distance on the optical axis) between the mth surface and the (m+1)th surface. Here, m is the surface number counted from the light incident side. In addition, nd represents the refractive index of each optical member with respect to the d-line, and νd represents the Abbe number of the optical member. The Abbe number νd of a certain material is given by Nd, NF, NC, and Ng, respectively, when the refractive indices at the Fraunhofer lines d-line (587.6 nm), F-line (486.1 nm), C-line (656.3 nm), and g-line (wavelength 435.8 nm) are νd=(Nd-1) / (NF-NC) It is expressed as:

[0078] In each numerical example, d, focal length (mm), F-number, and half angle of view (°) are all values ​​when the optical system IO of each example is focused on an object at infinity. "Back focus" is the distance on the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image surface expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the foreground (the lens surface closest to the object) of the optical system IO to the final surface plus the back focus.

[0079] If the optical surface is aspheric, a * symbol is added to the right of the surface number. The aspheric shape is expressed as follows, where X is the displacement from the apex of the surface in the optical axis direction, h is the height from the optical axis in a direction perpendicular to the optical axis, R is the paraxial radius of curvature, k is the conic constant, and A4, A6, A8, A10, and A12 are the aspheric coefficients of each order:

[0080]

number

[0081] In addition, "e±XX" in each aspheric coefficient is "×10± XX " It means.

[0082] (Numerical Example 1) Unit: mm Surface Data Surface number rd nd νd 1* -5.509 0.07 1.52000 50.3 2∞0.50 1.51680 64.2 3 ∞ 0.15 1.52000 50.3 4* 1.244 0.37 5 ∞ 0.40 1.51680 64.2 6 (Aperture) ∞ 0.29 1.52000 50.3 7* -0.678 2.08 8 ∞ 0.60 1.51680 64.2 9 ∞ 0.02 Image plane ∞ Aspheric Data Front page K = 2.35531e+01 A 4= 2.50149e-01 A 6=-1.75859e-01 A 8= 1.37283e-01 A10=-5.74951e-02 A12= 1.64602e-02 Side 4 K =-5.63858e+01 A 4= 5.12936e+00 A 6=-4.96025e+01 A 8= 4.80794e+02 A10=-2.37635e+03 A12= 5.14895e+03 Side 7 K =-2.17756e+00 A 4=-9.82178e-01 A 6= 3.80210e+00 A 8=-1.89409e+01 A10= 4.10014e+01 A12=-3.00511e+01 Various data Focal length 1.69 F-number: 2.94 Half angle of view (°) 40.54 Image height 1.45 Lens length 4.48 BF 0.02 (Numerical Example 2) Unit: mm Surface Data Surface number rd nd νd 1* -7.241 0.47 1.52000 52.0 2∞0.45 1.51680 64.2 3 ∞ 0.20 1.52000 52.0 4* 0.474 0.31 5* 1.211 0.05 1.52000 52.0 6 (Aperture) ∞ 0.65 1.51680 64.2 7 ∞ 0.19 1.52000 52.0 8* -0.652 0.60 9∞2.25 1.51680 64.2 10 ∞ 0.15 Image plane ∞ Aspheric Data Front page K =-8.83070e+24 A 4= 5.01855e-02 A 6=-2.87949e-02 A 8= 9.54976e-03 A10=-1.88167e-03 A12= 1.64587e-04 Side 4 K =-1.58737e+00 A 4= 3.26962e+00 A 6=-1.95957e+01 A 8= 3.68431e+02 A10=-2.52129e+03 A12= 7.56903e+03 5th page K = 0.00000e+00 A 4= 3.06379e-01 A 6=-8.73788e-01 A 8= 2.12766e+01 A10=-7.80674e+01 Side 8 K =-8.02137e+00 A 4=-2.89928e+00 A 6= 1.50497e+01 A 8=-5.84351e+01 A10= 1.36717e+02 A12=-1.03590e+02 Various data Focal length 1.26 F-number: 2.92 Half angle of view (°) 54.16 Image height 1.74 Lens length 5.33 BF 0.15 (Numerical Example 3) Unit: mm Surface Data Surface number rd nd νd 1* -4.316 0.03 1.52000 50.3 2∞0.50 1.51680 64.2 3 ∞ 0.15 1.52000 50.3 4* 1.464 0.35 5 ∞ 0.40 1.51680 64.2 6 (Aperture) ∞ 0.27 1.52000 50.3 7* -0.697 2.06 8 ∞ 0.10 1.52000 50.3 9 ∞ 0.60 1.51680 64.2 10∞0.01 Image plane ∞ Aspheric Data Front page K =-2.10617e+01 A 4= 1.74971e-01 A 6=-1.44608e-01 A 8= 1.24732e-01 A10=-6.22057e-02 A12= 8.82522e-03 Side 4 K =-1.28664e+02 A 4= 5.49992e+00 A 6=-5.93482e+01 A 8= 5.28007e+02 A10=-2.36376e+03 A12= 4.52864e+03 Side 7 K =-1.54368e+00 A 4=-6.27126e-01 A 6= 2.12523e+00 A 8=-1.08040e+01 A10= 1.91688e+01 A12=-7.87762e+00 Various data Focal length 1.76 F-number: 2.94 Half angle of view (°) 40.38 Image height 1.50 Lens length 4.48 BF 0.01 (Numerical Example 4) Unit: mm Surface Data Surface number rd nd νd 1 ∞ 0.50 1.51680 64.2 2 ∞ 0.15 1.52000 50.3 3* 2.814 0.26 4 ∞ 0.40 1.51680 64.2 5(Aperture) ∞ 0.15 1.52000 50.3 6* -0.832 1.87 7 ∞ 0.60 1.51680 64.2 8∞0.00 Image plane ∞ Aspheric Data 3rd page K =-3.69862e+01 A 4= 1.03853e+00 A 6=-8.76771e+00 A 8= 9.31896e+01 A10=-4.05184e+02 A12= 7.02136e+02 Page 6 K =-4.05569e+00 A 4=-9.48308e-01 A 6= 2.86374e+00 A 8=-1.27932e+01 A10= 2.26213e+01 A12=-9.63627e+00 Various data Focal length 2.00 F-number: 2.89 Half angle of view (°) 35.85 Image height 1.45 Lens length 3.88 BF 0.00 (Numerical Example 5) Unit: mm Surface Data Surface number rd nd νd 1* -11.062 0.10 1.52000 50.3 2∞0.50 1.51680 64.2 3 ∞ 0.15 1.52000 50.3 4* 1.289 0.35 5 ∞ 0.40 1.51680 64.2 6 (Aperture) ∞ 0.27 1.52000 50.3 7* -0.681 1.90 8 ∞ 0.10 1.52000 50.3 9 ∞ 0.60 1.51680 64.2 10∞0.00 Image plane ∞ Aspheric Data Front page K = 3.53565e+01 A 4= 1.92148e-01 A 6=-1.30036e-01 A 8= 6.08878e-02 A10= 2.79929e-02 A12=-2.80722e-02 Side 4 K =-5.52733e+01 A 4= 4.73926e+00 A 6=-4.67300e+01 A 8= 4.63193e+02 A10=-2.33351e+03 A12= 5.09030e+03 Side 7 K =-2.19034e+00 A 4=-9.14325e-01 A 6= 2.77824e+00 A 8=-1.26744e+01 A10= 2.32273e+01 A12=-1.08360e+01 Various data Zoom ratio 1.00 Focal length 1.71 F-number: 2.93 Half angle of view (°) 40.24 Image height 1.45 Lens length 4.38 BF 0.00 Various values ​​in each numerical example are summarized in Table 1 below.

[0083] [Table 1] EXAMPLES

[0084] FIG. 16 is a schematic diagram of the main part of the eyepiece of the HMD, which is an example of an electronic device having any of the imaging devices of the embodiments. The user sees a virtual image of an image displayed on a display (not shown) through an eyepiece OL. The user's eye EY is illuminated by a light source LS, and an image of the eye EY or an image of the light source LS reflected by the eye EY is acquired by the imaging device WL. At this time, the imaging device WL may acquire the above image through the eyepiece OL as shown in FIG. 16(a), or may acquire the image without the eyepiece OL as shown in FIG. 16(b). Here, the imaging device WL is any of the imaging devices described in the embodiments 1 to 5. For example, when using any of the imaging devices of the embodiments 1, 3 to 5, it is preferable to arrange the imaging device WL at an inclination of 25° with respect to the eye EY. Even if the subject and the imaging device WL are not directly facing each other in this way, a high image quality can be obtained by using the optical system IO of the embodiments 1 to 5. This makes it possible to acquire an image of the eye EY or an image of the light source LS reflected by the eye EY with high resolution. The acquisition unit not shown acquires information about the user using a signal from the imaging device WL. That is, the image capture device WL and the acquisition unit function as a detection system that performs highly accurate gaze detection and biometric authentication such as iris authentication.

[0085] In this embodiment, the light from the light source LS is preferably invisible light in order to prevent the user from feeling dazzled. Specifically, the emission wavelength of the light source LS is preferably about 700 nm or more and 1100 nm or less. If the wavelength exceeds 1100 nm, the sensitivity of the light receiving element may decrease, and the noise of the imaging device WL may increase.

[0086] In the present embodiment, the HMD has been described as an example of an electronic device having the imaging device of each embodiment, but the electronic device may be a finder section of a digital camera or a film camera.

[0087] The disclosure of this embodiment includes the following configuration. (Configuration 1) an optical system including a first substrate and an optical element having a refractive power disposed on the first substrate; a light receiving element having a light receiving surface on which an image is formed by the optical system; Let s be the distance from the optical axis of the optical system to the center of the light receiving surface, and Rimmax be the distance from the farthest position on the light receiving surface to the center, 0.2≦s / Rimmax≦1.1 An imaging apparatus characterized in that the following conditional expression is satisfied: (Configuration 2) the optical system includes a plane that is a boundary with air and is provided on an element made of glass or resin within an effective area that contributes to image formation; When the angle [°] of the plane with respect to the optical axis is θ, 0.5≦θ≦20.0 2. The imaging device according to claim 1, wherein the following condition is satisfied: (Configuration 3) a second substrate disposed adjacent to an image side of the first substrate; a first optical element having a negative refractive power is formed on an image side of the first substrate; 3. The imaging device according to claim 1, wherein a second optical element having a positive refractive power is formed on the image side of the second substrate. (Configuration 4) 4. The imaging device according to configuration 3, wherein each of the first optical element and the second optical element includes an aspheric surface. (Configuration 5) 5. The imaging device according to claim 3, wherein an aperture stop is formed on the second substrate. (Configuration 6) An imaging device described in any one of configurations 3 to 5, characterized in that a third optical element is formed on the object side of the first substrate, the end of the effective area contributing to image formation including an aspheric surface with positive refractive power. (Configuration 7) When the refractive power of the optical system is Φ and the refractive power of the second lens is Φ, 0.9≦Φ2i / Φ≦1.5 7. The imaging device according to any one of configurations 3 to 6, wherein the following condition is satisfied: (Configuration 8) When the refractive power of the optical system is Φ and the refractive power of the third optical element is Φ, 0.0≦|Φ1o / Φ|≦0.4 7. The imaging device according to configuration 6, wherein the following condition is satisfied: (Configuration 9) When the refractive power of the optical system is Φ and the refractive power of the first lens is Φ, -1.6≦Φ1i / Φ≦-0.2 9. The imaging device according to any one of configurations 3 to 8, wherein the following condition is satisfied: (Configuration 10) When the refractive power of the first lens is Φ1i and the refractive power of the second lens is Φ2i, -1.9≦Φ1i / Φ2i≦-0.1 10. The imaging device according to any one of configurations 3 to 9, wherein the following condition is satisfied: (Configuration 11) When the distance on the optical axis from the image side surface of the first lens to the image side surface of the second substrate is d12 and the focal length of the optical system is f, 0.1≦d12 / f≦2.0 11. The imaging device according to any one of configurations 3 to 10, wherein the following condition is satisfied: (Configuration 12) 12. The imaging device according to any one of configurations 1 to 11, wherein the optical element is made of a resin material. (Configuration 13) When the angle of view [°] in the direction connecting the center of the light receiving surface and the optical axis is ω, 35<ω<150 13. The imaging device according to any one of configurations 1 to 12, wherein the following condition is satisfied: (Configuration 14) When the focal length of the optical system is f [mm], 0 <f≦10 14. The imaging device according to any one of configurations 1 to 13, wherein the following condition is satisfied: (Configuration 15) Let f be the focal length of the optical system, and id be the distance from the surface of the optical system closest to the object to the object. 0.02≦f / id≦1.00 15. The imaging device according to any one of configurations 1 to 14, wherein the following condition is satisfied: (Configuration 16) a main optical system whose optical axis coincides with the center of the light receiving surface, 16. The imaging device according to any one of configurations 1 to 15, wherein the optical axis of the optical system is tilted with respect to the optical axis of the main optical system. (Configuration 17) 17. The imaging device according to any one of configurations 1 to 16, wherein the center of an effective area that contributes to image formation on the light receiving surface does not coincide with the center of the light receiving surface. (Configuration 18) an optical system including a first substrate and an optical element having a refractive power disposed on the first substrate; the optical system includes a plane that is a boundary with air and is provided on an element made of glass or resin within an effective area that contributes to image formation; When the angle [°] of the plane with respect to the optical axis of the optical system is θ, 0.5≦θ≦20.0 An imaging apparatus characterized in that the following conditional expression is satisfied: (Configuration 19) An imaging device according to any one of configurations 1 to 18; an acquisition unit that acquires information about a user using a signal from the imaging device.

[0088] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0089] C Center of the light receiving surface IO optical system OA optical axis

Claims

1. an optical system including a first substrate and an optical element having a refractive power disposed on the first substrate; a light receiving element having a light receiving surface on which an image is formed by the optical system; When the distance from the optical axis of the optical system to the center of the light receiving surface is s, and the distance from the farthest position on the light receiving surface from the center to the center is Rimmax, 0.2≦s / Rimmax≦1.1 An imaging apparatus characterized in that the following conditional expression is satisfied:

2. the optical system includes a plane that is a boundary with air and is provided on an element made of glass or resin within an effective area that contributes to image formation; When the angle [°] of the plane with respect to the optical axis is θ, 0.5≦θ≦20.0 2. The imaging apparatus according to claim 1, wherein the following condition is satisfied:

3. a second substrate disposed adjacent to an image side of the first substrate; a first optical element having a negative refractive power is formed on an image side of the first substrate; 3. The image pickup apparatus according to claim 1, further comprising a second optical element having a positive refractive power formed on an image side of the second substrate.

4. The imaging device according to claim 3 , wherein each of the first optical element and the second optical element includes an aspheric surface.

5. 4. The imaging device according to claim 3, wherein an aperture stop is formed on the second substrate.

6. 4. The imaging device according to claim 3, further comprising a third optical element formed on the object side of the first substrate, the third optical element including an aspheric surface with positive refractive power at an end of an effective area that contributes to image formation.

7. When the refractive power of the optical system is Φ and the refractive power of the second lens is Φ, 0.9≦Φ2i / Φ≦1.5 4. The imaging apparatus according to claim 3, wherein the following condition is satisfied:

8. When the refractive power of the optical system is Φ and the refractive power of the third optical element is Φ, 0.0≦|Φ1o / Φ|≦0.4 7. The imaging apparatus according to claim 6, wherein the following condition is satisfied:

9. When the refractive power of the optical system is Φ and the refractive power of the first lens is Φ, −1.6≦Φ1i / Φ≦−0.2 4. The imaging apparatus according to claim 3, wherein the following condition is satisfied:

10. When the refractive power of the first lens is Φ1i and the refractive power of the second lens is Φ2i, −1.9≦Φ1i / Φ2i≦−0.1 4. The imaging apparatus according to claim 3, wherein the following condition is satisfied:

11. When the distance on the optical axis from the image side surface of the first lens to the image side surface of the second substrate is d12 and the focal length of the optical system is f, 0.1≦d12 / f≦2.0 4. The imaging apparatus according to claim 3, wherein the following condition is satisfied:

12. 3. The imaging device according to claim 1, wherein the optical element is made of a resin material.

13. When the angle of view [°] in the direction connecting the center of the light receiving surface and the optical axis is ω, 35<ω<150 3. The image pickup apparatus according to claim 1, wherein the following condition is satisfied:

14. When the focal length of the optical system is f [mm], 0<f≦10 3. The image pickup apparatus according to claim 1, wherein the following condition is satisfied:

15. When the focal length of the optical system is f and the distance from the surface of the optical system closest to the object to the object is id, 0.02≦f / id≦1.0 3. The image pickup apparatus according to claim 1, wherein the following condition is satisfied:

16. a main optical system whose optical axis coincides with the center of the light receiving surface, 3. The imaging apparatus according to claim 1, wherein the optical axis of the optical system is tilted with respect to the optical axis of the main optical system.

17. 3. The imaging device according to claim 1, wherein the center of an effective area that contributes to image formation on said light receiving surface does not coincide with the center of said light receiving surface.

18. an optical system including a first substrate and an optical element having a refractive power disposed on the first substrate; the optical system includes a plane that is a boundary with air and is provided on an element made of glass or resin within an effective area that contributes to image formation; When the angle [°] of the plane with respect to the optical axis of the optical system is θ, 0.5≦θ≦20.0 An imaging apparatus characterized in that the following conditional expression is satisfied:

19. The imaging device according to claim 1 or 2, an acquisition unit that acquires information about a user using a signal from the imaging device.

Images