WO2018131264A1

WO2018131264A1 - Imaging unit and electronic device

Info

Publication number: WO2018131264A1
Application number: PCT/JP2017/039197
Authority: WO
Inventors: 典宏田部; 洋司崎岡; 茂幸馬場; 豪浅山
Original assignee: ソニーセミコンダクタソリューションズ株式会社
Priority date: 2017-01-12
Filing date: 2017-10-30
Publication date: 2018-07-19
Also published as: JP2018112677A

Abstract

[Problem] To make it possible to reduce the effects of aberration resulting from a WL-CSP structure. [Solution] This imaging unit is provided which comprises an imaging element where an image of a subject is formed, a lens optical system which is provided on the subject side of the imaging element and is fixed to the imaging element, and an imaging optical system which is provided between the subject and the lens optical system and which has a numerical aperture of NA. Defining λ as the wavelength of the light incident on the imaging element, θ[deg] as the angle of view and L(θ) as the optical path difference from an ideal lens for each angle of view θ, the surface shape of the lens optical system located on the subject side is a shape that satisfies expression (1).

Description

Imaging unit and electronic device

This disclosure relates to an imaging unit and an electronic device.

In recent years, WL-CSP (Wafer Level Chip Size Package) is often adopted as the structure of the imaging unit because the package can be reduced in size and thickness and is excellent in terms of manufacturing cost. . Since WL-CSP goes through a manufacturing process in which a lens optical system (cover glass or the like) is bonded to a wafer on which an image sensor is formed, and then the wafer provided with the lens optical system is separated into individual pieces. Is fixed to the image sensor and has an air layer between the cover glass and the image sensor. Patent Document 1 below discloses a technique in which a film having a specific gravity and a transparent resin are filled between an imaging element and a cover glass in WL-CSP.

JP 2014-175465 A

Here, with the existing technologies including the technology disclosed in Patent Document 1, it is difficult to reduce the influence of aberration caused by the cover glass fixed to the image sensor. For example, when light enters the imaging unit, passes through the cover glass, and forms an image on an imaging surface located between the cover glass and the imaging device, the influence of the aberration caused by the cover glass increases as the cover glass becomes thicker. Since it becomes large, the quality of a captured image falls.

In the imaging unit, it is conceivable to correct the aberration by changing the shape, material, etc. of the imaging optical system (for example, an imaging lens) provided on the subject side from the cover glass. Correction of aberrations becomes difficult.

Therefore, the present disclosure has been made in view of the above, and the present disclosure provides an imaging unit and an electronic apparatus that can further reduce the influence of aberration caused by the WL-CSP structure.

According to the present disclosure, an imaging device that forms an image of a subject, a lens optical system that is provided on the subject side of the imaging device and is fixed to the imaging device, and between the subject and the lens optical system An imaging optical system having a numerical aperture NA, and a wavelength of incident light incident on the imaging element is λ, an angle of view is θ [deg], and an ideal lens for each angle of view θ An imaging unit is provided in which when the optical path difference is L (θ), the surface shape of the lens optical system located on the subject side satisfies the following formula (1).

Further, according to the present disclosure, an imaging element on which an image of a subject is formed, a lens optical system that is provided on the subject side of the imaging element and is fixed to the imaging element, and the subject and the lens optical system An imaging optical system having a numerical aperture of NA, wherein the wavelength of incident light incident on the imaging element is λ, the field angle is θ [deg], and the maximum value of the field angle is θ The surface shape of the lens optical system located on the subject side is a shape that satisfies the following expression (2), where _max is the optical path difference with the ideal lens for each angle of view θ, and L (θ). An imaging unit is provided.

Further, according to the present disclosure, an imaging element on which an image of a subject is formed, a lens optical system that is provided on the subject side of the imaging element and is fixed to the imaging element, and the subject and the lens optical system An imaging optical system having a numerical aperture of NA, and the wavelength of incident light incident on the image sensor is λ, the field angle is θ [deg], and an ideal lens for each field angle θ The surface of the lens optical system located on the subject side when the optical path difference with the ideal lens for each angle of view θ of the imaging optical system is f (θ). An imaging unit having a shape that satisfies the following expression (3) is provided.

Further, according to the present disclosure, an imaging element on which an image of a subject is formed, a lens optical system that is provided on the subject side of the imaging element and is fixed to the imaging element, and the subject and the lens optical system An imaging optical system having a numerical aperture of NA, wherein the wavelength of incident light incident on the imaging element is λ, the field angle is θ [deg], and the maximum value of the field angle is θ _When the optical path difference with the ideal lens for each angle of view θ is L (θ) and the optical path difference with the ideal lens for each angle of view θ of the imaging optical system is f (θ), An imaging unit is provided in which the surface shape of the lens optical system located on the subject side satisfies the following expression (4).

Further, according to the present disclosure, an imaging element on which an image of a subject is formed, a lens optical system that is provided on the subject side of the imaging element and is fixed to the imaging element, and the subject and the lens optical system An imaging optical system having a numerical aperture of NA, and the wavelength of incident light incident on the image sensor is λ, the field angle is θ [deg], and an ideal lens for each field angle θ Provided by an electronic apparatus provided with an imaging unit, where the surface shape of the lens optical system located on the subject side is a shape satisfying the following expression (5), where L (θ) is the optical path difference between Is done.

Further, according to the present disclosure, an imaging element on which an image of a subject is formed, a lens optical system that is provided on the subject side of the imaging element and is fixed to the imaging element, and the subject and the lens optical system An imaging optical system having a numerical aperture of NA, wherein the wavelength of incident light incident on the imaging element is λ, the field angle is θ [deg], and the maximum value of the field angle is θ _Assuming that the optical path difference from the ideal lens for each angle of view θ is L (θ), the surface shape of the lens optical system located on the subject side is a shape that satisfies the following expression (6). An electronic device including an imaging unit is provided.

Further, according to the present disclosure, an imaging element on which an image of a subject is formed, a lens optical system that is provided on the subject side of the imaging element and is fixed to the imaging element, and the subject and the lens optical system An imaging optical system having a numerical aperture of NA, and the wavelength of incident light incident on the image sensor is λ, the field angle is θ [deg], and an ideal lens for each field angle θ The surface of the lens optical system located on the subject side when the optical path difference with the ideal lens for each angle of view θ of the imaging optical system is f (θ). An electronic device including an imaging unit is provided that has a shape that satisfies the following expression (7).

Further, according to the present disclosure, an imaging element on which an image of a subject is formed, a lens optical system that is provided on the subject side of the imaging element and is fixed to the imaging element, and the subject and the lens optical system An imaging optical system having a numerical aperture of NA, wherein the wavelength of incident light incident on the imaging element is λ, the field angle is θ [deg], and the maximum value of the field angle is θ _When the optical path difference with the ideal lens for each angle of view θ is L (θ) and the optical path difference with the ideal lens for each angle of view θ of the imaging optical system is f (θ), An electronic apparatus including an imaging unit is provided in which the surface shape of the lens optical system located on the subject side is a shape that satisfies the following formula (8).

According to the present disclosure, the aberration caused by the WL-CSP structure is corrected because the surface shape of the lens optical system located on the subject side has the predetermined shape as described above.

As described above, according to the present disclosure, it is possible to further reduce the influence of aberration caused by the WL-CSP structure.

Note that the above effects are not necessarily limited, and any of the effects shown in the present specification, or other effects that can be grasped from the present specification, together with or in place of the above effects. May be played.

It is a figure which shows the structure of the imaging unit which concerns on this indication. It is a figure which shows the optical path length from an imaging lens to an imaging surface in case a cover glass is not provided in an image pick-up element. It is a figure which shows the optical path length from an imaging lens to an imaging surface in case a flat cover glass is provided in an image pick-up element. It is a figure which shows the optical path length from an imaging lens to an imaging surface in case a cover glass which has the spherical shape of the curvature radius R on the surface is equipped with an image pick-up element. It is a figure which shows the relationship between the angle of view (theta) of incident light, and the square of an optical path difference in each curvature radius R. It is a graph which shows MTF in case a cover glass is not provided. It is a graph which shows MTF in case a flat cover glass is provided. It is a graph which shows MTF when the cover glass which has the spherical shape of the curvature radius R which concerns on a 1st Example on the surface is provided. It is a figure which shows the relationship between the plate | board thickness of a cover glass, and a curvature radius when the imaging unit which concerns on a 2nd Example is used for electronic devices, such as a smart phone. It is a figure which shows the optical path length from an imaging lens to an imaging surface in case the cover glass which has an aspherical structure is being fixed to the image pick-up element. It is a figure which shows the relationship between the field angle (theta) of incident light, and the square of an optical path difference in the cover glass which has a spherical shape, and the cover glass which has an aspherical shape. In a 4th Example, it is a figure which shows the relationship between the angle of view (theta) of incident light, and the square of an optical path difference. It is a figure which shows the function structure of an electronic device provided with the imaging unit which concerns on this indication. It is a block diagram which shows an example of a schematic structure of a vehicle control system. It is explanatory drawing which shows an example of the installation position of a vehicle exterior information detection part and an imaging part. It is a figure which shows an example of a schematic structure of an endoscopic surgery system. It is a block diagram which shows an example of a function structure of a camera head and CCU. It is a block diagram which shows an example of a schematic structure of an in-vivo information acquisition system.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

The description will be made in the following order.
1. Summary of disclosure 1. First embodiment Second Example 4 3. Third embodiment 4. Fourth embodiment 6. Functional configuration of an electronic device including an imaging unit according to the present disclosure Application example to a moving body 8. 8. Application example to endoscopic surgery system 9. Application example to in-vivo information acquisition system Remarks 11. Conclusion

<1. Summary of disclosure>
(1-1. Overview of the imaging unit 10)
First, an overview of the imaging unit 10 according to the present disclosure will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of an imaging unit 10 according to the present disclosure.

As shown in FIG. 1, the imaging unit 10 according to the present disclosure includes at least a cover glass 11 that is an example of a lens optical system, an imaging element 12, and an imaging lens 13 that is an example of an imaging optical system. The imaging unit 10 causes the imaging element 12 to form imaged image data representing the luminance distribution of the incident light by causing the incident light to form an image on the imaging surface by the imaging lens 13 and the cover glass 11. The imaging unit 10 according to the present disclosure can be used for electronic devices such as smartphones, digital cameras, personal computers, and tablet computers. However, these application examples are merely examples, and the imaging unit 10 according to the present disclosure can be used in various applications or apparatuses.

In addition, the cover glass 11 and the image sensor 12 in the present disclosure have a WL-CSP structure. That is, the cover glass 11 and the image sensor 12 are separated after the light-transmitting substrate (the substrate on which the cover glass 11 is based) is fixed on the semiconductor substrate in a wafer state on which the plurality of image sensors 12 are formed. It is a package manufactured by being done. WL-CSP performs package processing in the state of a wafer, so that the package can be reduced in size and thickness, and is excellent in terms of manufacturing cost.

The cover glass 11 is constructed by separating the light transmissive substrate into pieces, and transmits incident light. The cover glass 11 is positioned closer to the subject side than the image sensor 12, thereby transmitting incident light, and forming the incident light on an imaging surface positioned between the cover glass 11 and the image sensor 12. . That is, the cover glass 11 is formed of a material that can transmit light in a wavelength band to which light to be imaged on the image sensor 12 belongs (a material that can be regarded as transparent in the wavelength band of interest). . Further, in the manufacturing process of WL-CSP, the cover glass 11 is fixed to the image sensor 12, and the space between the cover glass 11 and the image sensor 12 is not hollow.

The imaging device 12 generates incident image data corresponding to the incident light by receiving and photoelectrically converting the incident light that has passed through the imaging lens 13 and the cover glass 11 and formed an image on the imaging surface. That is, the imaging device 12 is formed of a semiconductor substrate made of a semiconductor capable of detecting the incident light of interest. For example, when the wavelength band of the incident light of interest is a so-called visible light band, for example, an image sensor capable of color photographing having a Bayer array is used as the image sensor 12. The imaging device 12 may be various known devices such as a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor.

The imaging lens 13 transmits incident light incident on the imaging unit 10 and forms an image of the transmitted incident light on the imaging surface. Here, although a single lens is shown as the imaging lens 13 in FIG. 1, this is merely an example, and the imaging lens 13 may be an assembly of a plurality of lenses. In FIG. 1, the imaging lens 13 having a convex shape is shown. However, this is merely an example, and the imaging lens 13 having a concave shape, the imaging lens 13 having an aspherical structure, or the like. The shape of the imaging lens 13 is arbitrary. Further, the material of the imaging lens 13, the focal length, and the like are not particularly limited.

(1-2. Background)
The overview of the imaging unit 10 according to the present disclosure has been described above. Subsequently, the background of the present disclosure will be described.

In recent years, WL-CSP is often adopted as the structure of an imaging unit because the package can be reduced in size and thickness and is excellent in terms of manufacturing cost. As described above, the WL-CSP has a structure in which the cover glass is fixed to the imaging element and integrated in the manufacturing process.

Therefore, when light enters the imaging unit, passes through the cover glass, and forms an image on the imaging surface located between the cover glass and the imaging device, the influence of the aberration caused by the cover glass increases as the cover glass becomes thicker. Since it becomes large, the quality of a captured image falls. More specifically, when the cover glass is fixed to the image sensor as in the WL-CSP, the optical path difference from the ideal lens becomes larger as the cover glass becomes thicker. The influence of aberration etc. becomes large. When the influence of aberration increases, image disturbance such as defocusing and blurring occurs, and the quality of the captured image decreases.

Further, although it is conceivable to correct the aberration by changing at least one of the shape and material of the imaging lens, the aberration correction may become difficult as the cover glass becomes thicker.

The presenter of the present case has created the present disclosure while paying attention to the above circumstances. In the imaging unit 10 according to the present disclosure, the cover glass 11 having a shape such that the optical path difference with the ideal lens for each angle of view θ of the cover glass 11 is equal to or less than the depth of focus is used. Thereby, the imaging unit 10 according to the present disclosure can correct the aberration and improve the quality of the captured image. Hereinafter, an example of the present disclosure, a functional configuration of an electronic apparatus including the imaging unit 10 according to the present disclosure, application examples, and the like will be sequentially described.

<2. First Example>
The background of the present disclosure has been described above. Subsequently, a first example of the present disclosure will be described.

First, the influence of the aberration caused by the cover glass 11 will be described with reference to FIGS. FIG. 2 is a diagram showing the optical path length L from the imaging lens 13 to the imaging surface when the cover glass 11 is the image sensor 12.

As shown in FIG. 2, let us consider a case where the exit pupil distance of the imaging lens 13 is D [mm], and light of a predetermined wavelength is incident on the imaging lens 13 at an angle of view θ [deg]. At this time, the optical path length L from the imaging lens 13 to a predetermined imaging plane is simply expressed by the following formula (9). In the present specification, the angle of view θ refers to the direction of incident light with respect to the optical axis of the cover glass 11, and is represented by the angle formed by the optical axis direction and the traveling direction of incident light, as shown in FIG. Is done.

Subsequently, FIG. 3 will be described. FIG. 3 is a diagram schematically showing an optical path length L ′ from the imaging lens 13 to the imaging surface when the flat cover glass 11 is provided in the imaging device 12. FIG. 3 shows an optical path length L ′ when a flat glass plate having a thickness t and a refractive index n is provided as the cover glass 11 in the image sensor 12.

In FIG. 3, the plate thickness t of the cover glass 11 is expressed as t / n when converted to the distance between air. Accordingly, the distance between the imaging lens 13 and the cover glass 11 to be taken into account when correcting the focus shift caused by the provision of the cover glass 11 is Dt / n. Here, when incident light is incident at an angle of view θ, the relationship between the angle of view θ and the refraction angle θ ′ is expressed by sin θ = n × sin θ ′ according to Snell's law. Therefore, when a flat glass plate is provided in the image sensor 12 as the cover glass 11 as shown in FIG. 3, the optical path length L ′ from the imaging lens 13 to the imaging surface of the light incident at the angle of view θ is It is simply expressed by the following formula (10).

As is clear from a comparison of Equation (9) and Equation (10), the optical path length changes due to the influence of the flat cover glass 11, and aberration occurs. In other words, the value obtained by subtracting L represented by Equation (9) from L ′ represented by Equation (10) is the optical path difference caused by the provision of the flat cover glass 11, and this optical path difference is As a result, aberration occurs.

Subsequently, FIG. 4 will be described. FIG. 4 is a diagram showing the optical path length from the imaging lens 13 to the imaging surface when the imaging element 12 is provided with a cover glass 11 having a spherical shape with a radius of curvature R on the surface. As shown in FIG. 4, when the optical center of the imaging lens 13 is the origin, the intersection coordinates of the incident light and the cover glass 11 are expressed as a function of the radius of curvature R (x ′ (R), y ′ ( R)). Further, the angle formed by the optical axis and the straight line connecting the center of curvature of the cover glass 11 and the intersection point coordinates is φ (R) as a function of the radius of curvature R, and similarly, the refraction angle on the surface of the cover glass 11 is θ ″ (R). At this time, the optical path length L ″ from the imaging lens 13 to the imaging surface of the light beam incident at the angle of view θ is simply expressed by the following equation (11).

A value obtained by subtracting L represented by Equation (9) from L ″ represented by Equation (11) is an optical path difference caused by the provision of the cover glass 11 having a spherical surface with a radius of curvature R. In addition, when the aberration due to the optical path difference occurs, the exit pupil distance D, the plate thickness t of the cover glass 11 and the refractive index n are fixed values as shown in the above equation (11). Each of the other values is expressed by a function having the curvature radius R as a variable. Therefore, the optical path difference L ″ given by the equation (11) is also a function of the curvature radius R derived from the surface shape of the cover glass 11. Become.

In the imaging unit 10 according to the present embodiment, the optical path difference obtained by subtracting L represented by Expression (9) from L ″ represented by Expression (11) is equal to or less than the depth of focus at each angle of view θ. A cover glass 11 having a spherical surface with a radius of curvature R as described above is employed, where the numerical aperture of the imaging lens 13 is NA and the wavelength of incident light is λ [nm], the depth of focus. D _f is represented by the following formula (12).

That is, in the present embodiment, the shape of the cover glass 11 on the imaging lens 13 side (in other words, among the optical elements such as lenses constituting the lens optical system) so that the relationship of the following expression (13) is satisfied. , The shape of the lens located closest to the subject). Here, | Diff (θ, R) | indicates an optical path difference.

The depth of focus D _f is a tolerable range in the optical axis direction in which a clear image is considered to be formed practically. Therefore, as in this embodiment, the optical path difference at each angle of view θ is the depth of focus D _f. Thus, a clear image is formed regardless of the angle of view θ when light is incident. In other words, the aberration of the cover glass 11 can be corrected by the method of this embodiment, and the quality of the captured image can be improved.

Here, as an example, consider the case where the imaging unit 10 of this embodiment is used in an electronic device such as a smartphone. The F value of the imaging unit 10 mounted on an electronic device such as a smartphone is generally about 2.0. Accordingly, if the F value of the imaging lens 13 constituting the imaging unit 10 is 2.0, the numerical aperture NA of the imaging lens 13 is 0.25 according to the following formula (14) (in the formula, Describes the F value as "F").

In addition, electronic devices such as smartphones basically capture visible light. Here, when the wavelength λ of incident light to be detected is a median value of a general visible light wavelength band, and the median value is about 550 [nm], the depth of focus D is calculated based on the equation (12). _f is 4.4 [μm]. That is, when the imaging unit 10 of the present embodiment is used in an electronic device such as a smartphone, the optical path difference is desirably 4.4 [μm] or less based on the equation (13).

Further, not only the influence of the spherical aberration as described above but also the optical path difference may be calculated in consideration of the influence of astigmatism. More specifically, in an actual optical system, an optical path difference may occur due to the difference between the optical path length in the sagittal direction and the optical path length in the tangential direction due to the influence of astigmatism. Here, in the above Non-Patent Document 1 (Warren J. Smith “Modern Optical Engineering” 2007), the non-existence of light incident at an angle of view θ on a flat glass plate where the refractive index is n and the thickness is t. It is disclosed that the amount of point aberration AS (θ) is expressed by the following equation (15).

In the present embodiment, a value obtained based on AS (θ) of Expression (15) may be applied to Expression (13). For example, the optical path difference in consideration of astigmatism may be calculated by subtracting the value obtained by dividing AS (θ) in Expression (15) by 2 from the optical path difference in Expression (13). That is, the shape of the cover glass 11 may be calculated | required by the following formula | equation (16). Accordingly, the imaging unit 10 can correct aberrations including not only spherical aberration but also astigmatism, and can further improve the quality of the captured image. In addition, since Formula (16) is an example to the last, you may change suitably. For example, the mathematical formula for calculating the astigmatism amount AS based on the surface shape of the cover glass 11 (that is, the above formula (15)) may be appropriately changed.

The imaging unit 10 can generate a captured image with sufficient quality by satisfying the above expression (13) or (16), but the optical path difference from the ideal lens is as small as possible. More preferably, a cover glass 11 is used. Here, with reference to FIG. 5, the curvature radius R of the cover glass 11 which can make the optical path difference with an ideal lens as small as possible is demonstrated.

FIG. 5 shows a value given by the square of the optical path difference under the conditions where the exit pupil distance D is 4.0 [mm], the refractive index n is 1.5, and the plate thickness t is 0.2 [mm]. Is a view shown for each angle of view θ of incident light. The value of each variable is a value assumed for an electronic device including a small imaging device such as a smartphone or a digital camera.

As shown in FIG. 5, when the radius of curvature R of the cover glass 11 is infinite (indicated as “INF” in the figure) (that is, when the cover glass 11 is a flat plate), the radius of curvature R is The optical path difference is larger than in the case of other values. The optical path difference decreases as the radius of curvature R decreases from infinity, becomes minimum when the radius of curvature R is 50.7 [mm], and again when the radius of curvature R becomes smaller than 50.7 [mm]. growing. That is, when each variable is the above-mentioned condition, it is more preferable to employ the cover glass 11 having a curvature radius R of 50.7 [mm].

Subsequently, the defocus modulation transfer function (MTF: Modulation Transfer Function) characteristics of the imaging unit 10 will be described with reference to FIGS. 6 to 8, the horizontal axis indicates the defocus amount, and the vertical axis indicates the MTF intensity. 6 to 8 show MTFs when the angle of view θ of incident light is 0 [deg] and 30 [deg] as an example. When the angle of view θ of incident light is 30 [deg], the sagittal MTF and the tangential MTF are shown.

First, FIG. 6 will be described. FIG. 6 is a graph showing the MTF when the cover glass 11 is not provided. As shown in FIG. 6, in the case of the imaging unit 10 in which the aberration is corrected without the cover glass 11 being provided, when the defocus is 0, the MTF of each angle of view θ shows a good value. .

Subsequently, FIG. 7 will be described. FIG. 7 is a graph showing the MTF when the flat cover glass 11 is provided. As shown in FIG. 7, when the flat cover glass 11 is provided, the MTF when the angle of view θ of incident light is 0 [deg] shows a good value, but the angle of view θ of incident light. MTF deteriorates when is 30 [deg]. More specifically, when the angle of view θ of incident light is 30 [deg], the MTF peak position moves, so that the MTF when the defocus is 0 is lowered.

Next, FIG. 8 will be described. 8 is provided with a cover glass 11 having a spherical shape with a radius of curvature R according to the first embodiment (for example, the cover glass 11 when the radius of curvature R is 50.7 [mm]). It is a graph which shows MTF in a case. As shown in FIG. 8, when a cover glass 11 having a spherical surface with a radius of curvature R according to the present embodiment is provided on the surface, the MTF when the angle of view θ of incident light is 0 [deg] is obtained. Not only a good value is shown, but also the degradation of MTF when the angle of view θ of incident light is 30 [deg] is reduced. More specifically, when the angle of view θ of incident light is 30 [deg], the amount of movement of the peak position of the MTF is smaller than that in the example shown in FIG. 7, so the MTF when the defocus is 0 is Kept high.

<3. Second Embodiment>
The first embodiment of the present disclosure has been described above. Subsequently, a second embodiment of the present disclosure will be described.

In the first embodiment, it has optical path difference is determined radius of curvature R of the cover glass 11 to be equal to or less than the focal depth D _f of ideal lens at each angle theta. On the other hand, in the second embodiment, the average value of the optical path difference between the ideal lens at each angle of view θ is the curvature radius R to be equal to or less than the focal depth D _f is determined. That is, in the second embodiment, the following expression (17) or expression (18) is satisfied. Note that, similarly to the first embodiment, Expression (18) is a conditional expression when the influence of astigmatism (AS (θ) in Expression (15) above) is taken into consideration. By Expression (18), the imaging unit 10 can correct aberrations including astigmatism, and can further improve the quality of the captured image.

In particular, with regard to Expression (18), it is possible to realize sufficient imaging performance while relaxing the establishment conditions as compared with Expression (16) according to the first embodiment. In other words, as the optical path difference between the ideal lens in some angle θ is larger than the focal depth D _f, if the average value of the optical path difference between the ideal lens at each angle θ is familiar than the focal depth D _f Since Expression (18) is satisfied, sufficient imaging performance can be realized.

Considering the case where the imaging unit 10 according to the second embodiment is used in an electronic device such as a smartphone, the F value of the electronic device is set to 2.0 as in the first embodiment, and the incident light If the wavelength λ is 550 [nm], the average value of the optical path difference with the ideal lens at each angle of view θ is preferably 4.4 [μm] or less.

In addition, the angle of view θ of the imaging unit 10 mounted on an electronic device such as a smartphone is generally 80.0 [deg] or less, the refractive index n of the cover glass 11 is 1.5, and the focal length is generally It is assumed that it is 4.0 [mm]. Here, it is assumed that the focal length and the exit pupil distance D are the same. Then, by inputting these parameters into the equation (18), a curve having the curvature radius R and the plate thickness t as variables as shown in FIG. 9 is calculated. FIG. 9 shows a curve indicating the maximum condition of Expression (18) and a curve indicating the minimum condition of Expression (18). As shown in FIG. 9, the suitable radius of curvature R varies depending on the plate thickness t.

Furthermore, the following equation (19) is derived by performing linear approximation on each of the curve indicating the maximum condition of equation (18) and the curve indicating the minimum condition of equation (18) in FIG. 9 (in FIG. 9). (19) is also shown).

From the above, when the imaging unit 10 that satisfies Expression (19) is used in an electronic device such as a smartphone, the quality of the captured image can be improved by appropriately correcting the aberration caused by the cover glass 11. .

<4. Third Example>
The second embodiment of the present disclosure has been described above. Subsequently, a third embodiment of the present disclosure will be described.

In the first example and the second example, the cover glass 11 having a spherical shape with a radius of curvature R on the surface was used. That is, the cover glass 11 which is a spherical lens is used. On the other hand, in the following third embodiment, the case where the cover glass 11 is an aspheric lens will be described.

Here, the third embodiment will be described more specifically with reference to FIG. FIG. 10 is a diagram illustrating the optical path length from the imaging lens 13 to the imaging surface when the cover glass 11 having an aspherical structure is fixed to the imaging device 12.

Here, the shape of the surface of a general even-order aspherical lens well known as a lens having an aspherical structure is represented by the following formula (20). In Expression (20), Δx is the amount of deviation in the optical axis direction from the aspherical vertex, c is the reciprocal of the radius of curvature R of the aspherical lens (cover glass 11), k is the conic constant, α _i is an aspheric coefficient.

For example, assuming that the conic constant k is 0, the fourth-order aspheric coefficient is α ₄ , and the fourth-order aspheric coefficient is α ₆ , the incident light and the cover glass 11 in FIG. The intersection coordinates (Δx ′, y ′) are calculated by the following simultaneous equations (21) and (22).

Equation (21) and wherein the intersection coordinates as the solutions of the simultaneous equations (22) (△ x '( R, α 4, α 6), y' (R, α 4, α 6)) and, the intersection coordinates If the angle formed between the normal vector and the x-axis is φ ′, the angle formed between the normal vector and the light beam is θ + φ ′. Therefore, the refraction angle θ ″ of the light beam is expressed by sin (θ + φ ′) = n · sin θ ″. From the above, the optical path length can be calculated by the same method as the above equation (11).

Here, with reference to FIG. 11, the effect by making the surface of the cover glass 11 into an aspherical surface is demonstrated. FIG. 11 is a diagram showing the relationship between the angle of view θ of incident light and the square of the optical path difference when the surface of the cover glass 11 has a spherical shape and an aspherical shape. In the cover glass 11 having a spherical shape, the exit pupil distance D is set to 4.0 [mm], the refractive index n is set to 1.5, the plate thickness t is set to 0.2 [mm], and the radius of curvature R is set. The cover glass 11 is drawn under the condition of 50.8 [mm], and in the cover glass 11 having an aspheric shape, the fourth-order aspheric coefficient α _{4 is set} to 3 × 10 ⁻⁴ and the sixth-order aspheric coefficient α Plotted under conditions where ₆ is 5 × 10 ⁻⁵ .

Also in the third embodiment, the effect of astigmatism may be taken into account, as in the first embodiment. More specifically, in this embodiment, even if the optical path difference considering astigmatism is calculated by the same method as in the first embodiment, based on AS (θ) of the above formula (15). Good. Accordingly, the imaging unit 10 can correct aberrations including astigmatism, and can further improve the quality of the captured image. FIG. 11 shows an example in which the effect of astigmatism is taken into account.

In the example shown in FIG. 11, it can be seen that the cover glass 11 having an aspherical shape reduces the optical path difference from the ideal lens more than the cover glass 11 having a spherical shape. That is, the imaging unit 10 according to the third embodiment may be able to further reduce the influence of aberration caused by the cover glass 11 by making the surface shape of the cover glass 11 an aspherical shape.

<5. Fourth embodiment>
The third embodiment of the present disclosure has been described above. Subsequently, a fourth embodiment of the present disclosure will be described.

In the first to third embodiments, the influence of the aberration due to the imaging lens 13 was not taken into consideration. That is, it was a premise that the imaging lens 13 is an aberration-free lens. On the other hand, in the fourth embodiment, the influence of aberration caused by the imaging lens 13 is taken into consideration.

More specifically, the optical path difference with the ideal lens for each angle of view θ of the imaging lens 13 may be calculated, and the optical path difference may be used in the above formula (13) or formula (17). In addition, the calculation method of the optical path difference with the ideal lens for every angle of view θ of the imaging lens 13 is arbitrary. For example, the optical path difference between the imaging lens 13 and the ideal lens for each angle of view θ may be calculated based on design data of the imaging lens 13 or may be obtained from an actual measurement value.

The following equation (23) is obtained when f (θ) is applied to equation (13), where f (θ) is the optical path difference between the imaging lens 13 and the ideal lens for each angle of view θ. It is a relational expression.

The following expression (24) is a relational expression when f (θ) is applied to expression (17).

In the third embodiment, not only the aberration caused by the cover glass 11 but also the aberration caused by the imaging lens 13 is taken into consideration, and the quality of the captured image can be improved by appropriately correcting these aberrations.

Next, the optimum radius of curvature R when the aberration due to the imaging lens 13 is also considered will be described. FIG. 12 is a diagram showing the relationship between the angle of view θ of incident light and the square of the optical path difference in the fourth embodiment. In FIG. 12, the drawing is performed under conditions where the exit pupil distance D is 4.0 [mm], the refractive index n is 1.5, and the plate thickness t is 0.2 [mm].

Here, when the imaging lens 13 is not an aberration-free lens, that is, when the aberration due to the imaging lens 13 is not corrected well, the degree of field curvature by the imaging lens 13 is the angle of view θ of the incident light. It is proportional to the square. In FIG. 12, as an example, it is assumed that the optical path difference f (θ) between the imaging lens 13 and the ideal lens for each angle of view θ satisfies the following formula (25).

Also in the fourth embodiment, as in the first embodiment, the influence of astigmatism may be considered. More specifically, in this embodiment, even if the optical path difference considering astigmatism is calculated by the same method as in the first embodiment, based on AS (θ) of the above formula (15). Good. Accordingly, the imaging unit 10 can correct aberrations including astigmatism, and can further improve the quality of the captured image. FIG. 12 shows an example in which the effect of astigmatism is taken into account.

As shown in FIG. 12, when the imaging lens 13 is a non-aberration lens (in the first embodiment), the optical path difference from the ideal lens at the radius of curvature of 50.7 [mm], which is optimal, becomes large. On the other hand, it becomes the minimum when the curvature radius R is 33.0 [mm]. That is, when each variable is the above-mentioned conditions, it is more preferable to employ the cover glass 11 having a curvature radius R of 33.0 [mm].

<6. Functional configuration of electronic device including imaging unit according to present disclosure>
The fourth embodiment of the present disclosure has been described above. Subsequently, a functional configuration of the electronic device 100 such as a smartphone in which the imaging unit 10 according to the present disclosure is used will be described with reference to FIG. FIG. 13 is a diagram illustrating a functional configuration of the electronic device 100 including the imaging unit 10 according to the present disclosure.

As illustrated in FIG. 13, the electronic device 100 according to the present disclosure includes an imaging unit 10, an input information acquisition unit 20, a display control unit 30, a storage unit 40, and a control unit 50.

(Imaging unit 10)
The imaging unit 10 has the features and functions as described above, and can generate good captured image data by correcting aberrations according to the shape of the cover glass 11. The imaging unit 10 provides the generated captured image data to the control unit 50 described later. Since the configuration of the imaging unit 10 is as described above, detailed description thereof will be omitted below.

(Input information acquisition unit 20)
The input information acquisition unit 20 is an interface used for input by the user of the electronic device 100. For example, the input information acquisition unit 20 includes a button, a touch panel, a keyboard, a microphone, a pointing device, and the like, and the user inputs to the electronic device 100 using these devices. The input information acquisition unit 20 provides information input by the user to the control unit 50 described later. Note that the input information acquisition unit 20 may acquire input information from an external device including a button and provide the input information to the control unit 50.

(Display control unit 30)
The display control unit 30 controls display of various information. Specifically, the display control unit 30 includes a display device such as a display, and displays various types of information in various formats such as images, text, and graphs. The display control unit 30 may realize display by transmitting control information for display to an external device including a display or the like.

(Storage unit 40)
The storage unit 40 stores various parameters and databases, various programs, and the like that can be referred to when the control unit 50 described later performs various control processes. Further, the storage unit 40 may store temporary data generated when various control processes are performed by the control unit 50, various history information, and the like. The control unit 50 can freely perform data read / write processing on the storage unit 40. The storage unit 40 is realized by, for example, a ROM, a RAM, a storage device, and the like.

(Control unit 50)
The control unit 50 controls various processes in the electronic device 100. For example, the control unit 50 controls the imaging process by the imaging unit 10 based on the information input by the user, and controls the display process of the captured image by the display control unit 30. The process is merely an example, and the control unit 50 may appropriately control other various processes. The control unit 50 is realized by, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.

Note that the functional configuration of FIG. 13 is merely an example, and the functional configuration of the electronic device 100 according to the present disclosure may be changed as appropriate. Further, some of the functions of the electronic device 100 may be implemented by the control unit 50. For example, the control unit 50 may embody part of the functions of the imaging unit 10, the input information acquisition unit 20, the display control unit 30, or the storage unit 40.

<7. Application example to mobile objects>
The technology according to the present disclosure (present technology) can be applied to various products. For example, the technology according to the present disclosure is realized as a device that is mounted on any type of mobile body such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, and a robot. May be.

FIG. 14 is a block diagram illustrating a schematic configuration example of a vehicle control system that is an example of a mobile control system to which the technology according to the present disclosure can be applied.

The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in FIG. 14, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, a vehicle exterior information detection unit 12030, a vehicle interior information detection unit 12040, and an integrated control unit 12050. As a functional configuration of the integrated control unit 12050, a microcomputer 12051, an audio image output unit 12052, and an in-vehicle network I / F (interface) 12053 are illustrated.

The drive system control unit 12010 controls the operation of the device related to the drive system of the vehicle according to various programs. For example, the drive system control unit 12010 includes a driving force generator for generating a driving force of a vehicle such as an internal combustion engine or a driving motor, a driving force transmission mechanism for transmitting the driving force to wheels, and a steering angle of the vehicle. It functions as a control device such as a steering mechanism that adjusts and a braking device that generates a braking force of the vehicle.

The body system control unit 12020 controls the operation of various devices mounted on the vehicle body according to various programs. For example, the body system control unit 12020 functions as a keyless entry system, a smart key system, a power window device, or a control device for various lamps such as a headlamp, a back lamp, a brake lamp, a blinker, or a fog lamp. In this case, the body control unit 12020 can be input with radio waves transmitted from a portable device that substitutes for a key or signals from various switches. The body system control unit 12020 receives input of these radio waves or signals, and controls a door lock device, a power window device, a lamp, and the like of the vehicle.

The vehicle outside information detection unit 12030 detects information outside the vehicle on which the vehicle control system 12000 is mounted. For example, the imaging unit 12031 is connected to the vehicle exterior information detection unit 12030. The vehicle exterior information detection unit 12030 causes the imaging unit 12031 to capture an image outside the vehicle and receives the captured image. The vehicle outside information detection unit 12030 may perform an object detection process or a distance detection process such as a person, a car, an obstacle, a sign, or a character on a road surface based on the received image.

The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of received light. The imaging unit 12031 can output an electrical signal as an image, or can output it as distance measurement information. Further, the light received by the imaging unit 12031 may be visible light or invisible light such as infrared rays.

The vehicle interior information detection unit 12040 detects vehicle interior information. For example, a driver state detection unit 12041 that detects a driver's state is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that images the driver, and the vehicle interior information detection unit 12040 determines the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041. It may be calculated or it may be determined whether the driver is asleep.

The microcomputer 12051 calculates a control target value of the driving force generator, the steering mechanism, or the braking device based on the information inside / outside the vehicle acquired by the vehicle outside information detection unit 12030 or the vehicle interior information detection unit 12040, and the drive system control unit A control command can be output to 12010. For example, the microcomputer 12051 realizes an ADAS (Advanced Driver Assistance System) function including vehicle collision avoidance or impact mitigation, following traveling based on inter-vehicle distance, vehicle speed maintaining traveling, vehicle collision warning, or vehicle lane departure warning, etc. It is possible to perform cooperative control for the purpose.

Further, the microcomputer 12051 controls the driving force generator, the steering mechanism, the braking device, and the like based on the information around the vehicle acquired by the vehicle exterior information detection unit 12030 or the vehicle interior information detection unit 12040. It is possible to perform cooperative control for the purpose of automatic driving that autonomously travels without depending on the operation.

Further, the microcomputer 12051 can output a control command to the body system control unit 12020 based on information outside the vehicle acquired by the vehicle outside information detection unit 12030. For example, the microcomputer 12051 controls the headlamp according to the position of the preceding vehicle or the oncoming vehicle detected by the outside information detection unit 12030, and performs cooperative control for the purpose of anti-glare, such as switching from a high beam to a low beam. It can be carried out.

The sound image output unit 12052 transmits an output signal of at least one of sound and image to an output device capable of visually or audibly notifying information to a vehicle occupant or the outside of the vehicle. In the example of FIG. 14, an audio speaker 12061, a display unit 12062, and an instrument panel 12063 are illustrated as output devices. The display unit 12062 may include at least one of an on-board display and a head-up display, for example.

FIG. 15 is a diagram illustrating an example of an installation position of the imaging unit 12031.

In FIG. 15, the vehicle 12100 includes

imaging units

12101, 12102, 12103, 12104, and 12105 as the imaging unit 12031.

The

imaging units

12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as a front nose, a side mirror, a rear bumper, a back door, and an upper part of a windshield in the vehicle interior of the vehicle 12100. The imaging unit 12101 provided in the front nose and the imaging unit 12105 provided in the upper part of the windshield in the vehicle interior mainly acquire an image in front of the vehicle 12100. The

imaging units

12102 and 12103 provided in the side mirror mainly acquire an image of the side of the vehicle 12100. The imaging unit 12104 provided in the rear bumper or the back door mainly acquires an image behind the vehicle 12100. The forward images acquired by the

imaging units

12101 and 12105 are mainly used for detecting a preceding vehicle or a pedestrian, an obstacle, a traffic light, a traffic sign, a lane, or the like.

FIG. 15 shows an example of the shooting range of the imaging units 12101 to 12104. The imaging range 12111 indicates the imaging range of the imaging unit 12101 provided in the front nose, the imaging ranges 12112 and 12113 indicate the imaging ranges of the

imaging units

12102 and 12103 provided in the side mirrors, respectively, and the imaging range 12114 The imaging range of the imaging part 12104 provided in the rear bumper or the back door is shown. For example, by superimposing the image data captured by the imaging units 12101 to 12104, an overhead image when the vehicle 12100 is viewed from above is obtained.

At least one of the imaging units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the imaging units 12101 to 12104 may be a stereo camera including a plurality of imaging elements, or may be an imaging element having pixels for phase difference detection.

For example, the microcomputer 12051, based on the distance information obtained from the imaging units 12101 to 12104, the distance to each three-dimensional object in the imaging range 12111 to 12114 and the temporal change in this distance (relative speed with respect to the vehicle 12100). In particular, it is possible to extract, as a preceding vehicle, a three-dimensional object that travels at a predetermined speed (for example, 0 km / h or more) in the same direction as the vehicle 12100, particularly the closest three-dimensional object on the traveling path of the vehicle 12100. it can. Further, the microcomputer 12051 can set an inter-vehicle distance to be secured in advance before the preceding vehicle, and can perform automatic brake control (including follow-up stop control), automatic acceleration control (including follow-up start control), and the like. Thus, cooperative control for the purpose of autonomous driving or the like autonomously traveling without depending on the operation of the driver can be performed.

For example, the microcomputer 12051 converts the three-dimensional object data related to the three-dimensional object to other three-dimensional objects such as a two-wheeled vehicle, a normal vehicle, a large vehicle, a pedestrian, and a utility pole based on the distance information obtained from the imaging units 12101 to 12104. It can be classified and extracted and used for automatic avoidance of obstacles. For example, the microcomputer 12051 identifies obstacles around the vehicle 12100 as obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 determines the collision risk indicating the risk of collision with each obstacle, and when the collision risk is equal to or higher than the set value and there is a possibility of collision, the microcomputer 12051 is connected via the audio speaker 12061 or the display unit 12062. By outputting an alarm to the driver and performing forced deceleration or avoidance steering via the drive system control unit 12010, driving assistance for collision avoidance can be performed.

At least one of the imaging units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the captured images of the imaging units 12101 to 12104. Such pedestrian recognition is, for example, whether or not the user is a pedestrian by performing a pattern matching process on a sequence of feature points indicating the outline of an object and a procedure for extracting feature points in the captured images of the imaging units 12101 to 12104 as infrared cameras. It is carried out by the procedure for determining. When the microcomputer 12051 determines that there is a pedestrian in the captured images of the imaging units 12101 to 12104 and recognizes the pedestrian, the audio image output unit 12052 has a rectangular contour line for emphasizing the recognized pedestrian. The display unit 12062 is controlled so as to be superimposed and displayed. Moreover, the audio | voice image output part 12052 may control the display part 12062 so that the icon etc. which show a pedestrian may be displayed on a desired position.

Heretofore, an example of a vehicle control system to which the technology according to the present disclosure can be applied has been described. Of the configurations described above, the technology according to the present disclosure may be applied to the imaging unit 12031, for example. Specifically, the imaging unit 10 according to the present embodiment can be applied to the imaging unit 12031. By applying the imaging unit 10 to the imaging unit 12031, it is possible to generate a high-quality captured image in which aberrations are appropriately corrected.

<8. Application example to endoscopic surgery system>
The technology according to the present disclosure (present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

FIG. 16 is a diagram illustrating an example of a schematic configuration of an endoscopic surgery system to which the technology (present technology) according to the present disclosure can be applied.

FIG. 16 shows a state in which an operator (doctor) 11131 is performing an operation on a patient 11132 on a patient bed 11133 using an endoscopic operation system 11000. As shown in the figure, an endoscopic surgery system 11000 includes an endoscope 11100, other surgical instruments 11110 such as an insufflation tube 11111 and an energy treatment instrument 11112, and a support arm device 11120 that supports the endoscope 11100. And a cart 11200 on which various devices for endoscopic surgery are mounted.

The endoscope 11100 includes a lens barrel 11101 in which a region having a predetermined length from the distal end is inserted into the body cavity of the patient 11132, and a camera head 11102 connected to the proximal end of the lens barrel 11101. In the illustrated example, an endoscope 11100 configured as a so-called rigid mirror having a rigid lens barrel 11101 is illustrated, but the endoscope 11100 may be configured as a so-called flexible mirror having a flexible lens barrel. Good.

An opening into which the objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101. Irradiation is performed toward the observation target in the body cavity of the patient 11132 through the lens. Note that the endoscope 11100 may be a direct endoscope, a perspective mirror, or a side endoscope.

An optical system and an image sensor are provided inside the camera head 11102, and reflected light (observation light) from the observation target is condensed on the image sensor by the optical system. Observation light is photoelectrically converted by the imaging element, and an electrical signal corresponding to the observation light, that is, an image signal corresponding to the observation image is generated. The image signal is transmitted to a camera control unit (CCU: Camera Control Unit) 11201 as RAW data.

The CCU 11201 is configured by a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and the like, and comprehensively controls operations of the endoscope 11100 and the display device 11202. Further, the CCU 11201 receives an image signal from the camera head 11102 and performs various kinds of image processing for displaying an image based on the image signal, such as development processing (demosaic processing), for example.

The display device 11202 displays an image based on an image signal subjected to image processing by the CCU 11201 under the control of the CCU 11201.

The light source device 11203 is composed of a light source such as an LED (Light Emitting Diode), for example, and supplies irradiation light to the endoscope 11100 when photographing a surgical site or the like.

The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of irradiation light, magnification, focal length, etc.) by the endoscope 11100.

The treatment instrument control device 11205 controls the drive of the energy treatment instrument 11112 for tissue ablation, incision, blood vessel sealing, or the like. In order to inflate the body cavity of the patient 11132 for the purpose of securing the field of view by the endoscope 11100 and securing the operator's work space, the pneumoperitoneum device 11206 passes gas into the body cavity via the pneumoperitoneum tube 11111. Send in. The recorder 11207 is an apparatus capable of recording various types of information related to surgery. The printer 11208 is a device that can print various types of information related to surgery in various formats such as text, images, or graphs.

In addition, the light source device 11203 that supplies the irradiation light when the surgical site is imaged to the endoscope 11100 can be configured by, for example, a white light source configured by an LED, a laser light source, or a combination thereof. When a white light source is configured by a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high accuracy. Therefore, the light source device 11203 adjusts the white balance of the captured image. It can be carried out. In this case, laser light from each of the RGB laser light sources is irradiated on the observation target in a time-sharing manner, and the drive of the image sensor of the camera head 11102 is controlled in synchronization with the irradiation timing, thereby corresponding to each RGB. It is also possible to take the images that have been taken in time division. According to this method, a color image can be obtained without providing a color filter in the image sensor.

Further, the driving of the light source device 11203 may be controlled so as to change the intensity of the output light every predetermined time. Synchronously with the timing of changing the intensity of the light, the drive of the image sensor of the camera head 11102 is controlled to acquire an image in a time-sharing manner, and the image is synthesized, so that high dynamic without so-called blackout and overexposure A range image can be generated.

Further, the light source device 11203 may be configured to be able to supply light of a predetermined wavelength band corresponding to special light observation. In special light observation, for example, by utilizing the wavelength dependence of light absorption in body tissue, the surface of the mucous membrane is irradiated by irradiating light in a narrow band compared to irradiation light (ie, white light) during normal observation. A so-called narrow band imaging is performed in which a predetermined tissue such as a blood vessel is imaged with high contrast. Alternatively, in special light observation, fluorescence observation may be performed in which an image is obtained by fluorescence generated by irradiating excitation light. In fluorescence observation, the body tissue is irradiated with excitation light to observe fluorescence from the body tissue (autofluorescence observation), or a reagent such as indocyanine green (ICG) is locally administered to the body tissue and applied to the body tissue. It is possible to obtain a fluorescence image by irradiating excitation light corresponding to the fluorescence wavelength of the reagent. The light source device 11203 can be configured to be able to supply narrowband light and / or excitation light corresponding to such special light observation.

FIG. 17 is a block diagram showing an example of the functional configuration of the camera head 11102 and CCU 11201 shown in FIG.

The camera head 11102 includes a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 includes a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other by a transmission cable 11400 so that they can communicate with each other.

The lens unit 11401 is an optical system provided at a connection portion with the lens barrel 11101. Observation light taken from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is configured by combining a plurality of lenses including a zoom lens and a focus lens.

The imaging unit 11402 includes an imaging element. One (so-called single plate type) image sensor may be included in the imaging unit 11402, or a plurality (so-called multi-plate type) may be used. In the case where the imaging unit 11402 is configured as a multi-plate type, for example, image signals corresponding to RGB may be generated by each imaging element, and a color image may be obtained by combining them. Alternatively, the imaging unit 11402 may be configured to include a pair of imaging elements for acquiring right-eye and left-eye image signals corresponding to 3D (Dimensional) display. By performing the 3D display, the operator 11131 can more accurately grasp the depth of the living tissue in the surgical site. Note that in the case where the imaging unit 11402 is configured as a multi-plate type, a plurality of lens units 11401 can be provided corresponding to each imaging element.

Further, the imaging unit 11402 is not necessarily provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101 immediately after the objective lens.

The driving unit 11403 is configured by an actuator, and moves the zoom lens and the focus lens of the lens unit 11401 by a predetermined distance along the optical axis under the control of the camera head control unit 11405. Thereby, the magnification and the focus of the image captured by the imaging unit 11402 can be adjusted as appropriate.

The communication unit 11404 is configured by a communication device for transmitting and receiving various types of information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 as RAW data to the CCU 11201 via the transmission cable 11400.

Further, the communication unit 11404 receives a control signal for controlling driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head control unit 11405. The control signal includes, for example, information for designating the frame rate of the captured image, information for designating the exposure value at the time of imaging, and / or information for designating the magnification and focus of the captured image. Contains information about the condition.

Note that the imaging conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. Good. In the latter case, a so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function are mounted on the endoscope 11100.

The camera head control unit 11405 controls driving of the camera head 11102 based on a control signal from the CCU 11201 received via the communication unit 11404.

The communication unit 11411 is configured by a communication device for transmitting and receiving various types of information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

Further, the communication unit 11411 transmits a control signal for controlling driving of the camera head 11102 to the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, or the like.

The image processing unit 11412 performs various types of image processing on the image signal that is RAW data transmitted from the camera head 11102.

The control unit 11413 performs various types of control related to imaging of the surgical site by the endoscope 11100 and display of a captured image obtained by imaging of the surgical site. For example, the control unit 11413 generates a control signal for controlling driving of the camera head 11102.

Further, the control unit 11413 causes the display device 11202 to display a picked-up image showing the surgical part or the like based on the image signal subjected to the image processing by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition techniques. For example, the control unit 11413 detects surgical tools such as forceps, specific biological parts, bleeding, mist when using the energy treatment tool 11112, and the like by detecting the shape and color of the edge of the object included in the captured image. Can be recognized. When displaying the captured image on the display device 11202, the control unit 11413 may display various types of surgery support information superimposed on the image of the surgical unit using the recognition result. Surgery support information is displayed in a superimposed manner and presented to the operator 11131, thereby reducing the burden on the operator 11131 and allowing the operator 11131 to proceed with surgery reliably.

The transmission cable 11400 for connecting the camera head 11102 and the CCU 11201 is an electric signal cable corresponding to electric signal communication, an optical fiber corresponding to optical communication, or a composite cable thereof.

Here, in the illustrated example, communication is performed by wire using the transmission cable 11400. However, communication between the camera head 11102 and the CCU 11201 may be performed wirelessly.

In the foregoing, an example of an endoscopic surgery system to which the technology according to the present disclosure can be applied has been described. Of the configurations described above, the technology according to the present disclosure can be applied to, for example, the imaging unit 11402 of the camera head 11102. Specifically, the imaging unit 10 according to the present embodiment can be applied to the imaging unit 11402 of the camera head 11102. By applying the imaging unit 10 to the imaging unit 11402 of the camera head 11102, it is possible to generate a high-quality captured image in which aberrations are appropriately corrected.

Note that although an endoscopic surgery system has been described here as an example, the technology according to the present disclosure may be applied to, for example, a microscope surgery system and the like.

<9. Application example for in-vivo information acquisition system>
The technology according to the present disclosure (present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

FIG. 18 is a block diagram illustrating an example of a schematic configuration of a patient in-vivo information acquisition system using a capsule endoscope to which the technique (present technique) according to the present disclosure can be applied.

The in-vivo information acquisition system 10001 includes a capsule endoscope 10100 and an external control device 10200.

The capsule endoscope 10100 is swallowed by the patient at the time of examination. The capsule endoscope 10100 has an imaging function and a wireless communication function, and moves inside the organ such as the stomach and the intestine by peristaltic motion or the like until it is spontaneously discharged from the patient. Images (hereinafter also referred to as in-vivo images) are sequentially captured at predetermined intervals, and information about the in-vivo images is sequentially wirelessly transmitted to the external control device 10200 outside the body.

The external control device 10200 comprehensively controls the operation of the in-vivo information acquisition system 10001. Further, the external control device 10200 receives information about the in-vivo image transmitted from the capsule endoscope 10100 and, based on the received information about the in-vivo image, displays the in-vivo image on the display device (not shown). The image data for displaying is generated.

In the in-vivo information acquisition system 10001, an in-vivo image obtained by imaging the inside of the patient's body can be obtained at any time in this manner until the capsule endoscope 10100 is swallowed and discharged.

The configurations and functions of the capsule endoscope 10100 and the external control device 10200 will be described in more detail.

The capsule endoscope 10100 includes a capsule-type casing 10101. In the casing 10101, a light source unit 10111, an imaging unit 10112, an image processing unit 10113, a wireless communication unit 10114, a power supply unit 10115, and a power supply unit 10116 and the control unit 10117 are stored.

The light source unit 10111 is composed of a light source such as an LED (Light Emitting Diode), for example, and irradiates the imaging field of the imaging unit 10112 with light.

The image capturing unit 10112 includes an image sensor and an optical system including a plurality of lenses provided in front of the image sensor. Reflected light (hereinafter referred to as observation light) of light irradiated on the body tissue to be observed is collected by the optical system and enters the image sensor. In the imaging unit 10112, in the imaging element, the observation light incident thereon is photoelectrically converted, and an image signal corresponding to the observation light is generated. The image signal generated by the imaging unit 10112 is provided to the image processing unit 10113.

The image processing unit 10113 is configured by a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), and performs various signal processing on the image signal generated by the imaging unit 10112. The image processing unit 10113 provides the radio communication unit 10114 with the image signal subjected to signal processing as RAW data.

The wireless communication unit 10114 performs predetermined processing such as modulation processing on the image signal that has been subjected to signal processing by the image processing unit 10113, and transmits the image signal to the external control apparatus 10200 via the antenna 10114A. In addition, the wireless communication unit 10114 receives a control signal related to drive control of the capsule endoscope 10100 from the external control device 10200 via the antenna 10114A. The wireless communication unit 10114 provides a control signal received from the external control device 10200 to the control unit 10117.

The power feeding unit 10115 includes a power receiving antenna coil, a power regeneration circuit that regenerates power from a current generated in the antenna coil, a booster circuit, and the like. In the power feeding unit 10115, electric power is generated using a so-called non-contact charging principle.

The power supply unit 10116 is composed of a secondary battery, and stores the electric power generated by the power supply unit 10115. In FIG. 18, in order to avoid complication of the drawing, illustration of an arrow or the like indicating a power supply destination from the power supply unit 10116 is omitted, but the power stored in the power supply unit 10116 is stored in the light source unit 10111. The imaging unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the control unit 10117 can be used for driving them.

The control unit 10117 includes a processor such as a CPU, and a control signal transmitted from the external control device 10200 to drive the light source unit 10111, the imaging unit 10112, the image processing unit 10113, the wireless communication unit 10114, and the power feeding unit 10115. Control accordingly.

The external control device 10200 is configured by a processor such as a CPU or GPU, or a microcomputer or a control board in which a processor and a storage element such as a memory are mounted. The external control device 10200 controls the operation of the capsule endoscope 10100 by transmitting a control signal to the control unit 10117 of the capsule endoscope 10100 via the antenna 10200A. In the capsule endoscope 10100, for example, the light irradiation condition for the observation target in the light source unit 10111 can be changed by a control signal from the external control device 10200. In addition, an imaging condition (for example, a frame rate or an exposure value in the imaging unit 10112) can be changed by a control signal from the external control device 10200. Further, the contents of processing in the image processing unit 10113 and the conditions (for example, the transmission interval, the number of transmission images, etc.) by which the wireless communication unit 10114 transmits an image signal may be changed by a control signal from the external control device 10200. .

Further, the external control device 10200 performs various image processing on the image signal transmitted from the capsule endoscope 10100, and generates image data for displaying the captured in-vivo image on the display device. As the image processing, for example, development processing (demosaic processing), high image quality processing (band enhancement processing, super-resolution processing, NR (Noise reduction) processing and / or camera shake correction processing, etc.), and / or enlargement processing ( Various signal processing such as electronic zoom processing can be performed. The external control device 10200 controls driving of the display device to display an in-vivo image captured based on the generated image data. Alternatively, the external control device 10200 may cause the generated image data to be recorded on a recording device (not shown) or may be printed out on a printing device (not shown).

Heretofore, an example of the in-vivo information acquisition system to which the technology according to the present disclosure can be applied has been described. The technology according to the present disclosure can be applied to, for example, the imaging unit 10112 among the configurations described above. The imaging unit 10 according to the present embodiment can be applied to the imaging unit 10112. By applying the imaging unit 10 to the imaging unit 10112, it is possible to generate a high-quality captured image in which aberrations are appropriately corrected.

<10. Remarks>
In the first to fourth embodiments described above, the refraction phenomenon of the cover glass 11 is used as the aberration correcting means. However, the present invention is not limited to this, and the aberration may be corrected by using the cover glass 11 having the same shape as that of the diffractive lens on the surface. At this time, similarly to the case where the cover glass 11 having an aspherical shape on the surface is used (third embodiment), by defining a new parameter representing the surface shape of the cover glass 11, the An optical path difference is required. Then, the optical path difference is the shape of the cover glass 11 to be equal to or less than the focal depth D _f is determined. The imaging lens 13 may also be a diffractive lens.

Further, in the first to fourth embodiments, the cover glass 11 and the image sensor 12 have a WL-CSP structure, and the cover glass 11 is light transmissive fixed on the image sensor 12. It was formed by scraping the conductive substrate (the substrate on which the cover glass 11 is based). However, the present invention is not limited to this. For example, the cover glass 11 may be formed by loading an optical resin on the image sensor 12.

<11. Conclusion>
As described above, in the imaging unit 10 according to the present disclosure, a cover glass 11 having the shape as the optical path difference is equal to or less than the focal depth D _f of the ideal lens of each angle θ of the cover glass 11 is used. Thereby, the imaging unit 10 according to the present disclosure can correct the aberration and improve the quality of the captured image.

The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the technical scope of the present disclosure is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field of the present disclosure can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that it belongs to the technical scope of the present disclosure.

In addition, the effects described in this specification are merely illustrative or illustrative, and are not limited. That is, the technology according to the present disclosure can exhibit other effects that are apparent to those skilled in the art from the description of the present specification in addition to or instead of the above effects.

The following configurations also belong to the technical scope of the present disclosure.
(1)
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
When the wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], and the optical path difference from the ideal lens for each angle of view θ is L (θ), it is located on the subject side. An imaging unit in which the surface shape of the lens optical system is a shape that satisfies the following expression (26).

(2)
When the maximum value of the angle of view is θ _max , the surface shape of the lens optical system located on the subject side is a shape that satisfies the following expression (27).
The imaging unit according to (1).

(3)
When the optical path difference with the ideal lens for each angle of view θ of the imaging optical system is f (θ), the surface shape of the lens optical system located on the subject side satisfies the following expression (28). It has a shape,
The imaging unit according to any one of (1) and (2).

(4)
When the maximum value of the angle of view is θ _max [deg], the surface shape of the lens optical system located on the subject side is a shape that satisfies the following expression (29).
The imaging unit according to (3).

(5)
When the thickness of the lens optical system is t [mm] and the refractive index is n, the optical path difference L (θ) is based on the astigmatism amount AS (θ) expressed by the following equation (30). Is corrected,
The imaging unit according to any one of (1) to (4).

(6)
At least a part of a portion where the incident light is incident on the surface of the lens optical system on the subject side has a convex structure with a radius of curvature R.
The imaging unit according to any one of (2) and (4).
(7)
The curvature radius R satisfies the following formula (31) when the thickness of the lens optical system is t [mm].
The imaging unit according to (6).

(8)
The object side surface of the lens optical system has an aspherical structure,
The imaging unit according to any one of (1) to (5).
(9)
The object side surface of the lens optical system has a diffractive structure;
The imaging unit according to any one of (1) to (5).
(10)
The lens optical system is formed of an optical resin;
The imaging unit according to any one of (1) to (9).
(11)
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the maximum value of the angle of view is θ _max , and the optical path difference from the ideal lens for each angle of view θ is L (θ ), The surface shape of the lens optical system located on the subject side is a shape that satisfies the following expression (32).

(12)
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the optical path difference L (θ) with respect to the ideal lens for each angle of view θ, and the angle of view of the image pickup optical system. An imaging unit in which the surface shape of the lens optical system located on the subject side satisfies the following expression (33), where f (θ) is the optical path difference from the ideal lens for each θ. .

(13)
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the maximum value of the angle of view is θ _max , and the optical path difference from the ideal lens for each angle of view θ is L (θ ) And the surface shape of the lens optical system located on the subject side is given by the following equation (34) where f (θ) is the optical path difference between the imaging optical system and the ideal lens for each angle of view θ. The imaging unit has a shape satisfying

(14)
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
When the wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], and the optical path difference from the ideal lens for each angle of view θ is L (θ), it is located on the subject side. An electronic apparatus including an imaging unit, wherein the surface shape of the lens optical system is a shape that satisfies the following expression (35).

(15)
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the maximum value of the angle of view is θ _max , and the optical path difference from the ideal lens for each angle of view θ is L (θ ), The surface shape of the lens optical system located on the subject side is an electronic apparatus including an imaging unit that satisfies the following expression (36).

(16)
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the optical path difference from the ideal lens for each angle of view θ is L (θ), and the angle of view of the image pickup optical system is An imaging unit in which the surface shape of the lens optical system located on the object side satisfies the following expression (37), where f (θ) is the optical path difference from the ideal lens for each θ. Electronic equipment comprising.

(17)
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the maximum value of the angle of view is θ _max , and the optical path difference from the ideal lens for each angle of view θ is L (θ ), And the surface shape of the lens optical system located on the subject side is expressed by the following equation (38), where f (θ) is the optical path difference between the imaging optical system and the ideal lens for each angle of view θ. An electronic device including an imaging unit that has a shape satisfying

DESCRIPTION OF SYMBOLS 100 Electronic device 10 Imaging unit 11 Cover glass 12 Imaging element 13 Imaging lens 20 Input information acquisition part 30 Display control part 40 Storage part 50 Control part

Claims

An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
When the wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], and the optical path difference from the ideal lens for each angle of view θ is L (θ), it is located on the subject side. An imaging unit in which the surface shape of the lens optical system is a shape that satisfies the following expression (1).
When the maximum value of the angle of view is θ max , the surface shape of the lens optical system located on the subject side is a shape that satisfies the following expression (2).
The imaging unit according to claim 1.
When the optical path difference with the ideal lens for each angle of view θ of the imaging optical system is f (θ), the surface shape of the lens optical system located on the subject side satisfies the following expression (3). It has a shape,
The imaging unit according to claim 1.
When the maximum value of the angle of view is θ max [deg], the surface shape of the lens optical system located on the subject side is a shape that satisfies the following expression (4).
The imaging unit according to claim 3.
When the thickness of the lens optical system is t [mm] and the refractive index is n, the optical path difference L (θ) is based on the astigmatism amount AS (θ) expressed by the following equation (5). Is corrected,
The imaging unit according to claim 1.
At least a part of a portion where the incident light is incident on the surface of the lens optical system on the subject side has a convex structure with a radius of curvature R.
The imaging unit according to claim 2.
The curvature radius R satisfies the following expression (6) when the thickness of the lens optical system is t [mm].
The imaging unit according to claim 6.
The object side surface of the lens optical system has an aspherical structure,
The imaging unit according to claim 1.
The object side surface of the lens optical system has a diffractive structure;
The imaging unit according to claim 1.
The lens optical system is formed of an optical resin;
The imaging unit according to claim 1.
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the maximum value of the angle of view is θ max , and the optical path difference from the ideal lens for each angle of view θ is L (θ ), The surface shape of the lens optical system located on the subject side is a shape that satisfies the following expression (7).
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the optical path difference L (θ) with respect to the ideal lens for each angle of view θ, and the angle of view of the image pickup optical system. An imaging unit in which the surface shape of the lens optical system located on the object side satisfies the following expression (8), where f (θ) is the optical path difference from the ideal lens for each θ. .
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the maximum value of the angle of view is θ max , and the optical path difference from the ideal lens for each angle of view θ is L (θ ) And the surface shape of the lens optical system located on the subject side is expressed by the following equation (9) where f (θ) is the optical path difference between the imaging optical system and the ideal lens for each angle of view θ. The imaging unit has a shape satisfying
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
When the wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], and the optical path difference from the ideal lens for each angle of view θ is L (θ), it is located on the subject side. An electronic apparatus provided with an imaging unit, wherein the lens optical system has a surface shape that satisfies the following expression (10).
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the maximum value of the angle of view is θ max , and the optical path difference from the ideal lens for each angle of view θ is L (θ ), The surface shape of the lens optical system located on the subject side is an electronic apparatus including an imaging unit that satisfies the following formula (11).
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the optical path difference from the ideal lens for each angle of view θ is L (θ), and the angle of view of the image pickup optical system is An imaging unit in which the surface shape of the lens optical system located on the object side satisfies the following expression (12), where f (θ) is the optical path difference from the ideal lens for each θ. Electronic equipment comprising.
An image sensor that forms an image of a subject;
A lens optical system provided on the subject side of the image sensor and fixed to the image sensor;
An imaging optical system having a numerical aperture of NA provided between the subject and the lens optical system,
The wavelength of incident light incident on the image sensor is λ, the angle of view is θ [deg], the maximum value of the angle of view is θ max , and the optical path difference from the ideal lens for each angle of view θ is L (θ ), And f (θ) is the optical path difference with the ideal lens for each angle of view θ of the imaging optical system, the surface shape of the lens optical system located on the subject side is expressed by the following equation (13) An electronic device including an imaging unit that has a shape satisfying