JP2006030723A - Imaging apparatus and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus which has a small-sized and inexpensive constitution, and effectively reduces moire, and records images of high quality, and also to provide an electronic apparatus using the same. <P>SOLUTION: The imaging apparatus includes; an imaging element 111 which is provided with a plurality of light receiving elements 101 arrayed like a matrix and converts incident light Lin to an image signal; and a low pass filter 110 provided in the incidence side of the imaging element 111. The low pass filter 110 has a prism group consisting of prism elements provided with at least a refracting face, and the refracting face refracts the incident light to a prescribed direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for an imaging apparatus and an electronic apparatus.

  As an imaging device, for example, a digital video camera that converts incident light into an electrical signal by a light receiving element and stores an image of a subject as digital data has become widespread. The light receiving elements used in an imaging apparatus such as a digital video camera are regularly arranged corresponding to the pixels. When the pixel structure in the imaging device and the pattern of the subject overlap with the same period, moire may occur in an image recorded in the imaging device. Moire is recorded in the imaging device due to the periodic pattern of the subject and the periodic structure in the imaging device. Moire may occur when an image is reproduced because the recorded image overlaps with a periodic structure in a reproduction device that reproduces the image. Moire causes a drop in image quality by causing colors and patterns that do not exist in the original subject to appear. Conventionally, as a technique for reducing moire, for example, there are techniques proposed in Patent Documents 1 and 2.

JP 2001-330799 A JP-A-5-2151

  Patent Documents 1 and 2 disclose a configuration using a birefringent plate or a diffraction grating as a low-pass filter. A low-pass filter reduces the periodicity of an image by dividing incident light. The periodicity of the image can be effectively reduced as the number of incident light divisions is increased. On the other hand, when a birefringent plate is used as a low-pass filter, it is necessary to provide a thick birefringent plate as the number of incident light divisions is increased. If a thick birefringent plate is required, the imaging device will be large and expensive. In some cases, a polarizing plate is required together with the birefringent plate. Therefore, it is difficult for an imaging apparatus using a birefringent plate to effectively reduce moire in a small and inexpensive configuration. Further, when a diffraction grating is used as a low-pass filter, the contrast of an image may be lowered due to generation of high-order diffracted light.

  As described above, the conventional technique is problematic because it is difficult to effectively reduce moire and record a high-quality image with a small and inexpensive configuration. The present invention has been made in view of the above-described problems, and provides an imaging apparatus capable of effectively reducing moire and recording a high-quality image with a small and inexpensive configuration, and an electronic apparatus using the imaging apparatus. The purpose is to do.

  In order to solve the above-described problems and achieve the object, according to the present invention, an image sensor that includes a plurality of light receiving elements arranged in a matrix and converts incident light into an image signal, and an incident side of the image sensor A low-pass filter, and the low-pass filter includes a prism group including prism elements each having at least a refracting surface, and the refracting surface refracts incident light in a predetermined direction. Can be provided.

  The light from the subject enters the prism group, and then the optical path is bent in a predetermined direction. For example, when a plurality of refractive surfaces are provided on the prism element, the image of the subject is divided into a plurality of parts and projected onto the imaging element. For example, when the subject has a periodic pattern, the periodicity of the pattern is weakened by dividing the subject image into a plurality of images. By reducing the periodicity of the image of the subject, the light interference effect caused by the regular arrangement of the light receiving elements is reduced. Furthermore, since the periodicity of the image of the subject is weakened, the occurrence of moire due to the periodic structure of the image reproduction device can be reduced. The prism group divides incident light according to the direction and number of refractive surfaces of the prism elements. By increasing the number of refracting surfaces in different directions, the number of incident light divisions can be increased even in a thin prism group. For example, when a prism group is manufactured by a molding technique, it is easy to increase the number of refractive surfaces of the prism element. For this reason, moire can be effectively reduced in a small and inexpensive configuration. Further, unlike the case where a diffraction grating is used as a low-pass filter, the image contrast is not lowered by unnecessary high-order diffracted light. Thereby, it is possible to obtain an imaging apparatus capable of effectively reducing moire and recording a high-quality image with a small and inexpensive configuration.

  Further, as a preferred aspect of the present invention, the refracting surface includes the direction of the refracting surface that guides the incident light to the light receiving element adjacent to the light receiving element at the incident position when the incident light travels straight through the prism group, and the refractive surface. And an angle formed by a reference plane formed in a direction substantially perpendicular to the optical axis. The direction in which the optical path of the incident light is bent can be controlled by the direction of the refracting surface. The degree of refraction of incident light (the refraction angle) can be controlled by the angle of the refracting surface with respect to the reference surface. By providing the refracting surface with a predetermined direction and a predetermined angle, the incident light is guided to the light receiving element adjacent to the light receiving element on which the incident light traveling without being refracted by the prism group enters. As a result, the periodicity of the subject image can be weakened.

  As a preferred aspect of the present invention, the prism group has two sets of prism elements each having a substantially trapezoidal cross-sectional shape in the first direction and having a longitudinal direction in a second direction substantially orthogonal to the first direction. It is desirable that the two sets of prism elements are provided so that their longitudinal directions are substantially orthogonal to each other, and the trapezoidal slope corresponds to the refracting surface. The cross-sectional shape of the prism element in the first direction is a substantially trapezoidal shape. The trapezoidal slope acts as a refractive surface. For this reason, an image of light refracted on the inclined surface can be formed in a direction orthogonal to the longitudinal direction of the prism element. In this embodiment, the longitudinal directions of the two sets of prism elements are further substantially orthogonal to each other. This can weaken the periodicity of the subject image.

  As a preferred aspect of the present invention, it is desirable that the prism element has at least four refracting surfaces, and the four refracting surfaces have different directions. For example, a prism element having four refracting surfaces can branch incident light in four directions. Moire can be effectively reduced by branching incident light in at least four directions.

  According to a preferred aspect of the present invention, the prism group includes at least a first prism element having a first shape and a second prism element having a second shape different from the first shape. It is desirable to have. For example, the prism group includes a first prism element that refracts incident light in four directions, up, down, left, and right, and a second prism element that refracts incident light in four directions, upper right, lower right, upper left, and lower left. It can be. The first prism element and the second prism element may be different in the direction in which incident light is refracted, and may have different refracting surface sizes. Thus, by providing differently shaped prism elements, the periodicity due to the provision of the prism elements in the prism group is weakened, and transmitted light can be prevented from interfering with each other. Thereby, a reduction in contrast of the image can be reduced.

  Further, according to a preferred aspect of the present invention, it is desirable to have an imaging lens that guides incident light to the imaging device, and the prism group is provided in an optical path between the imaging lens and the imaging device. By providing a prism element in the optical path between the imaging lens and the imaging element, the subject image can be divided into a plurality of parts.

  Further, according to a preferred aspect of the present invention, the image pickup lens for guiding incident light to the image pickup device is provided, and the prism group is located at the pupil position of the image pickup lens, a position conjugate to the pupil position, the vicinity of the pupil position, or the pupil position. It is desirable to be provided near the conjugate position. The pupil position of the imaging lens has the highest light beam density. In other words, the light beam diameter is smallest at the pupil position. Therefore, if the prism group is arranged in the vicinity of the pupil position, the size of the prism group can be reduced. For this reason, the imaging lens itself provided with a prism group can also be reduced in size. The prism group can be easily manufactured and processed with high processing accuracy. Thereby, a small and inexpensive imaging device can be obtained.

  According to a preferred aspect of the present invention, the edge of the boundary of the prism element that is substantially perpendicular to the straight line along the diameter of the substantially circular shape in the substantially circular region having a unit area determined by the F number of the imaging lens. It is desirable that the number of is 50 or less. By setting the number of edges of the prism elements substantially perpendicular to the straight line along the diameter of the circular shape of the unit area to be 50 or less, the influence of diffraction due to the periodic structure of the prism group is suppressed, and the diffraction light A reduction in contrast can be reduced. Further, in a substantially circular region having a unit area defined by the F-number of the imaging lens, the number of edges of the prism element boundary substantially perpendicular to the straight line along the diameter of the substantially circular shape may be 30 or less. desirable. Thereby, the influence of the diffraction resulting from the periodic structure of the prism group can be further suppressed, and the reduction in contrast due to the diffracted light can be reduced. More preferably, in a substantially circular region having a unit area determined by the F-number of the imaging lens, the number of edges of the prism element boundary substantially perpendicular to a straight line along the diameter of the substantially circular shape is 15 or less. It is desirable. Thereby, an imaging apparatus capable of recording a higher quality image can be obtained.

  Moreover, as a preferable aspect of the present invention, it is desirable to have a holding unit that holds the prism group at a predetermined position with respect to the position of the image pickup element by fixing the image pickup element and the prism group. In order for the incident light refracted by the refracting surface to accurately enter the light receiving element adjacent to the light receiving element that enters when the light travels straight through the prism group, it is necessary to position the imaging element and the prism group. By providing the holding portion, the incident light refracted by the refracting surface can be accurately incident on the adjacent light receiving element. Thereby, moire can be reduced effectively.

  Furthermore, according to the present invention, it is possible to provide an electronic apparatus having an imaging device. Since the image pickup apparatus is provided, it is possible to effectively reduce moire with a small and inexpensive configuration, and to reduce the occurrence of diffraction phenomenon due to the periodicity of the prism group. Thereby, a reduction in contrast can be avoided, and an electronic device capable of recording a high-quality image can be obtained.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration of an imaging apparatus 100 according to Embodiment 1 of the present invention. The imaging apparatus 100 converts incident light Lin into an electrical signal by the light receiving element 101, and stores an object image as digital data. The imaging apparatus 100 includes a plurality of light receiving elements 101 and includes an imaging element 111 that converts incident light Lin into an image signal. The image sensor 111 arranges the light receiving element 101 on a plane substantially perpendicular to the optical axis AX. Each light receiving element 101 is arranged in a matrix in two directions substantially orthogonal to each other on a plane substantially perpendicular to the optical axis AX. As the light receiving element 101, for example, a CCD or a CMOS sensor can be used.

  The light shielding portion 103 is provided on the incident side of the image sensor 111 corresponding to the area between the light receiving elements 101. The light blocking unit 103 blocks the light that travels to the position between the light receiving elements 101 in the incident light Lin, thereby preventing the generation of stray light that causes noise in the light receiving elements 101. A color filter layer 105 is provided on the incident side of the layer where the light shielding portion 103 is provided. The color filter layer 105 is provided with a color filter 104 corresponding to the light receiving element 101. The color filter 104 includes an R light transmission color filter that transmits R light, a G light transmission color filter that transmits G light, and a B light transmission color filter that transmits B light. Incident light Lin is divided into R light, G light, and B light by passing through each color filter 104.

  On the incident side of the color filter layer 105, a microlens array 106 is provided. The microlens array 106 condenses incident light Lin on each light receiving element 101. On the incident side of the micro lens array 106, an infrared cut filter 107, a prism group 110, and an imaging lens 120 are sequentially provided. The infrared cut filter 107 blocks infrared light in the incident light Lin.

  FIG. 2 shows a perspective configuration of the prism group 110. The prism group 110 is formed on the exit side surface of a transparent plate made of glass or transparent resin. The prism group 110 is a low-pass filter provided on the incident side of the image sensor 111. The prism group 110 includes a plurality of prism elements 201 having a refractive surface and a flat surface.

  Returning to FIG. 1, the imaging apparatus 100 includes a prism group 110 in the optical path between the imaging lens 120 and the imaging element 111. The imaging lens 120 guides the incident light Lin to the imaging element 111. The image sensor 111 and the prism group 110 are fixed by a holding unit 112. The holding unit 112 holds the prism group 110 at a predetermined position with respect to the position of the image sensor 111. The image sensor 111 is fixed to the fixed surface 114 of the holding unit 112. The prism group 110 is fixed to the fixed surface 113 of the holding unit 112. The positional relationship between the prism group 110 and the image sensor 111 will be described later.

  Incident light Lin from the subject is guided toward the image sensor 111 by the imaging lens 120. Incident light Lin that has passed through the imaging lens 120 passes through the prism group 110 and the infrared cut filter 107 and enters the microlens array 106. Incident light Lin incident on the microlens array 106 is refracted in a direction to be condensed on each light receiving element 101 by the microlens element. Incident light Lin transmitted through the microlens array 106 is divided into R light, G light, and B light by the color filter layer 105. The color filter layer 105 has a role of giving color information to the image signal.

  Incident light Lin divided into each color light enters each light receiving element 101. The incident light Lin is incident on the light receiving element 101 at a position corresponding to the position on the subject. Each light receiving element 101 converts incident light Lin into an image signal by photoelectric conversion. Image signals obtained by the respective light receiving elements of the image sensor 111 are recorded in a memory or a recording medium (not shown). In this way, the imaging apparatus 100 stores the subject image as digital data.

  FIG. 3 illustrates the behavior of the incident light Lin from the subject OBJ to the imaging plane SI. Here, only the configuration necessary for the description is illustrated. The imaging plane SI is, for example, the surface of the image sensor 111. For example, consider a case where an image of the object point Q of the subject OBJ is formed on the imaging plane SI. The subject OBJ and the imaging plane SI are in a conjugate relationship with each other. Incident light Lin from the object point Q of the subject OBJ diffuses from the object point Q at an angle θ1 and enters the imaging lens 120. The imaging lens 120 converts the angle of the incident light Lin so as to condense the diffusing incident light Lin at the light receiving element 101, which is a point P0 on the imaging plane SI in FIG.

  The prism group 110 shown in FIG. 3 has a cross-sectional configuration when the prism group 110 is cut along a plane including the optical axis. In such a cross-sectional configuration, the prism element 201 can be represented by two refractive surfaces SA and SB and a flat portion SC between the refractive surfaces SA and SB. Of the incident light Lin, light incident on the flat portion SC travels in the traveling direction as it is without being refracted. The light that has passed through the flat part SC is collected with the image point P0 of the imaging plane SI as a focal point.

When the imaging lens 120 having an F number of F is used, the angle θ1 of the light Lin that can be captured by the imaging lens 120 can be expressed by the following conditional expression.
θ1 = asin {1 / (2F)}
Light that spreads from the object point Q at an angle θ1 passes through a region M on the prism group 110 including a plurality of prism elements 201 and enters the image point P0 at an angle θ1.

  Here, the light beam Lin from the object point Q shown in FIG. 3 toward the imaging plane SI passes through the prism group 110 provided in the optical path. The area of the region M on the prism group 110 through which the light beam from the object point Q is transmitted is defined as a unit area. The region M is a substantially circular region. The light Lin traveling from the object point Q toward the image sensor 111 travels in the refraction direction determined by the direction of the refraction surface in the region M. The light Lin passes through the prism group 110 and then enters the light receiving elements in the respective refraction directions with a light amount with an intensity corresponding to the proportion occupied by the refracting surface in the same direction in the unit area.

  The refracting surfaces SA and SB refract incident light in a predetermined direction. Of the incident light Lin, light incident on the refractive surface SA is refracted by the refractive surface SA. The light that has passed through the refracting surface SA has its optical path bent, and is focused on the image point P1 on the imaging surface SI. Of the incident light Lin, light incident on the refractive surface SB is refracted by the refractive surface SB. The light passing through the refracting surface SB is condensed with the optical path being bent and the image point P2 on the imaging surface SI as a focal point.

  4 and 5 are plan views showing the configuration of the prism group 110. FIG. Each prism element 201 has a substantially square shape as shown in FIG. Each light receiving element 101 is arranged in a matrix in two directions substantially orthogonal to each other on a plane substantially perpendicular to the optical axis AX, whereas each prism element 201 has a side 211a of each prism element 201 that receives light. It is configured to form approximately 45 ° with respect to the two directions in which the elements 101 are arranged. The prism group 110 shown in FIG. 3 shows a cross section when passing through the approximate center of each prism element 201 and cutting along a plane along the side 211a.

  FIG. 6 is an enlarged view showing the vicinity of the prism group 110. Consider a case where a medium (for example, air) between the prism group 110 and the image sensor 111 has a refractive index n1, and members constituting the prism group 110 have a refractive index n2. The refracting surface 212 is formed so as to have an angle θ with respect to a reference surface 213 a obtained by extending the flat portion 213. Hereinafter, the angle θ is referred to as an inclination angle of the refractive surface 212.

For the sake of simplicity, the parallel light of the light Lin from the subject OBJ will be described. A light beam incident on the flat portion 213 enters the flat portion 213 perpendicularly. Therefore, the light travels straight and enters the light receiving element 101 without being refracted by the flat portion 213. On the other hand, the light incident on the refractive surface 212 is refracted so as to satisfy the following conditional expression.
n1 · sinβ = n2 · sinα
Here, the angle α is an incident angle based on the normal line N of the refractive surface 212, and the angle β is an exit angle.

In addition, in the image sensor 111 that is separated from the prism group 110 by a distance L, the position of the straight light, the position of the refracted light, and the distance S are expressed by the following equations.
S = L × tan Δβ
Δβ = β-α
Thus, the distance S can be arbitrarily set by controlling the inclination angle θ of the refracting surface 212. The distance S is the amount of movement of the image of the subject OBJ on the image sensor 111. Further, as is apparent from FIG. 6, the direction in which the light beam LL2 is refracted depends on the direction of the refracting surface 212. In other words, by controlling the direction of the refracting surface 212, the direction in which an image is formed in the image sensor 111 can be arbitrarily set.

  Returning to FIG. 5, it is assumed that one side of the square prism element 201 has a length La and one side of the flat portion 213 has a length Lb. An area La × La occupied by one prism element 201 in the prism group 110 is defined as a unit area. The flat part 213 has an area FS = Lb × Lb. The four refractive surfaces 212a, 212b, 212c, and 212d have areas P1, P2, P3, and P4, respectively.

  Here, the amount of light that has traveled straight through the flat portion 213 corresponds to the area FS of the flat portion 213 occupying the unit area. Similarly, the total amount of light refracted by the four refracting surfaces 212a, 212b, 212c, and 212d corresponds to the total area P1 + P2 + P3 + P4 of the refracting surfaces 212a, 212b, 212c, and 212d occupying the unit area. Here, if the areas P1, P2, P3, and P4 of the four refracting surfaces 212a, 212b, 212c, and 212d are substantially equal, the total area is P1 + P2 + P3 + P4 = 4 × P1. In other words, by controlling the area of the flat portion 213 or the refracting surface 212, the amount of light that has traveled straight or refracted through the prism element 201 in the imaging element 111 can be arbitrarily set.

  Considering the amount of light at the image sensor 111, it is desirable that the amount of light that has traveled straight through the flat portion 213 and the amount of light refracted by the refracting surface 212 be equal. For example, when the length La = 1.0 and the length Lb = 0.707, the unit area of the prism element 201 is 1.0 (= 1.0 × 1.0), and the area FS of the flat portion 213 is 0.00. 5 (= 0.707 × 0.707). The total area (4 × P1) of the four refracting surfaces 212a, 212b, 212c, and 212d having the same area is 0.5 (= 1.0−0.5). In this way, the amount of light that passes straight through the flat portion 213 and the total amount of light refracted by the four refracting surfaces 212a, 212b, 212c, and 212d can be made equal.

  FIG. 7 shows the light condensed at the point P0 on the imaging plane SI. A region M on the prism group 110 including the plurality of prism elements 201 is a circle having a radius of L × tan θ1. Of the light that has passed through the region M, the light that has passed through the flat portion 213 enters the point P0 at an angle θ1. The amount of light incident on the point P0 can be set by the area of the flat portion 213 occupying the region M. The direction in which the image is shifted is determined by the orientation of the refractive surface 212 of the prism element 201 provided in the region M. In the region M, the light transmitted through the surface in the same direction enters the same point on the imaging surface SI. Accordingly, the light transmitted through the region M is incident on the light receiving elements in the respective refraction directions with a light amount with an intensity corresponding to the proportion of the region M occupied by the same-direction surface.

  FIG. 8 shows light passing through the point N on the prism group 110. Light passing through the point N is incident at an angle θ1 from the subject OBJ. The light from the point Q1 on the surface SO on the subject OBJ is incident on the point PQ1 on the imaging surface SI. The light from the point Q2 on the surface SO on the subject OBJ is incident on the point PQ2 on the imaging surface SI. The light from the point Q0 on the surface SO on the subject OBJ is incident on the point PQ0 on the imaging surface SI.

  FIG. 9 shows the arrangement of the light receiving elements 101 in the image sensor 111. R, G, and B shown in FIG. 9 indicate that an R light transmission color filter, a G light transmission color filter, and a B light transmission color filter are provided for each light receiving element 101. FIG. 10 illustrates an image formed on the image sensor 111. For example, it is assumed that the image PI <b> 1 is formed at the position of the light receiving element 101 </ b> R by the light that is substantially perpendicularly incident on the flat portion 213 of the prism element 201 going straight.

  Light incident on the refracting surface 212a (see FIG. 5) of the prism element 201 undergoes a refracting action with a refraction direction, a refraction amount, and a refraction amount corresponding to the direction of the refraction surface 212a, the inclination angle θ, and the area P1. The light refracted by the refracting surface 212a travels to the position of the light receiving element 101Ba that is diagonally right above the light receiving element 101R. An image PI2 is formed at a position separated from the image PI1 by a distance S in the diagonally upper right direction by the refractive surface 212a. In the following description, for the sake of simplicity, it is assumed that there is no up / down / left / right reversal of the image due to the imaging action of the imaging lens 120.

  The light refracted by the refracting surface 212b travels to the position of the light receiving element 101Bb that is obliquely upper left with respect to the light receiving element 101R. An image PI3 is formed at a position separated from the image PI1 by a distance S in the diagonally upper left direction by the refractive surface 212b. The light refracted by the refracting surface 212c travels to the position of the light receiving element 101Bc that is obliquely lower left with respect to the light receiving element 101R. By the refracting surface 212c, the image PI4 is formed at a position separated from the image PI1 by a distance S in the diagonally downward left direction.

  The light refracted by the refracting surface 212d travels to the position of the light receiving element 101Bd that is obliquely lower right with respect to the light receiving element 101R. An image PI4 is formed at a position separated from the image PI1 by a distance S in the diagonally downward right direction by the refractive surface 212d. The four refractive surfaces 212a, 212b, 212c, and 212d of the prism element 201 are provided in different directions in order to refract light in different directions.

  As described above, the refracting surface 212 guides the incident light to the light receiving elements 101Ba, 101Bb, 101Bc, and 101Bd adjacent to the light receiving element 101R at the incident position when the incident light travels straight through the prism group 110. The refracting surfaces 212a, 212b, 212c, and 212d of the prism element 201 have directions and angles that guide incident light to the light receiving elements 101Ba, 101Bb, 101Bc, and 101Bd.

  For example, when the subject OBJ has a periodic pattern, the periodicity of the pattern is weakened by dividing the image of the subject OBJ into a plurality of parts. By reducing the periodicity of the image of the subject OBJ, the light interference effect caused by the regular arrangement of the light receiving elements 101 is reduced. Further, since the periodicity of the image of the subject OBJ is weakened, the occurrence of moire due to the periodic structure of the image reproducing device can be reduced.

  The prism group 110 divides incident light according to the direction and number of the refractive surfaces 212 of the prism element 201. By increasing the number of refracting surfaces 212 in different directions, the number of incident light divisions can be increased even in the thin prism group 110. For example, when the prism group 110 is manufactured by a molding technique, it is easy to increase the number of refractive surfaces 212 of the prism element 201. For example, if a replication technique by injection molding is used, the prism element 201 can be manufactured at low cost. For this reason, moire can be effectively reduced in a small and inexpensive configuration. Further, unlike the case where a diffraction grating is used as a low-pass filter, the image contrast is not lowered by unnecessary high-order diffracted light. As a result, it is possible to effectively reduce moiré and to record a high-quality image with a small and inexpensive configuration.

  Here, with reference to FIGS. 23A and 23B, the configuration of the prism group capable of reducing the influence of the diffracted light will be described. For example, the first prism element 2311 having the first shape in the region M defined by the F number of the imaging lens 120 as in the group 2310 of the prism having the upper surface configuration illustrated in FIG. Consider a configuration in which a second prism element 2312 having a second shape different from the first shape is provided. The first shape of the first prism element 2311 is a shape in which incident light can be refracted in four directions of upper, lower, left, and right shown in FIG. The second shape of the second prism element 2312 is the four directions of upper right, lower right, upper left, and lower left shown in FIG. 23-1 by four refractive surfaces in directions different from those of the first prism element 2311. It is a shape that can refract incident light. The first prism element 2311 and the second prism element 2312 are arranged in the region M at a predetermined ratio. Thus, by providing the prism group 2310 with a plurality of prism elements 2311 and 2312 having different shapes, incident light can be refracted in a predetermined ratio and in a predetermined direction.

  Thus, by providing prism elements having different shapes, the periodicity of the prism group is weakened, and transmitted light can be prevented from interfering with each other. Thereby, a reduction in contrast of the image can be reduced. Note that the first prism element and the second prism element may have different refracting surface sizes in addition to different directions in which incident light is refracted. Further, the shape of the prism element is not limited to two types, and may be two or more types.

  If the number of edges at the boundary of the prism element that is substantially perpendicular to the straight line MS is large, diffraction of the transmitted light may be caused. The prism group 2310 is configured such that the two prism elements are in contact with the straight line MS on the diameter of the region M regardless of the region M taken at any position. In this case, the number of edges 2313 at the boundary of the prism elements 2311 on the straight line MS is four. The prism group 2320 having the cross-sectional configuration A and the upper surface configuration B in FIG. 23-2 includes four prism elements 2321 on the straight line MS in the region M. In other words, the prism element 2321 is provided so that the frequency is 4 on the straight line MS in the region M. Further, the number of edges 2323 at the boundary of the prism elements 2321 on the straight line MS is 11.

  As described above, in the prism group, at least one prism element (period) or more may be arranged on a straight line along an arbitrary diameter within a unit area determined by the F number of the imaging lens 120. desirable. Thereby, the light rays incident on the light receiving element can be made uniform, and moire can be effectively reduced. Further, it is desirable that the number of edges at the boundary of the prism elements substantially perpendicular to the straight line along the diameter in the region M having the unit area is 50 or less. By setting the number of edges at the boundary of the prism elements substantially perpendicular to the straight line along the diameter in the region M to 50 or less, the influence of diffraction due to the periodic structure of the prism group is suppressed, and the contrast is reduced by the diffracted light. Can be reduced.

  Furthermore, it is desirable that the number of edges at the boundary of the prism elements substantially perpendicular to the straight line along the diameter in the region M having a unit area determined by the F number of the imaging lens is 30 or less. Thereby, it is possible to further suppress the influence of diffraction due to the periodic structure of the prism group and reduce the decrease in contrast due to the diffracted light. More preferably, the number of edges at the boundary of the prism elements substantially perpendicular to the straight line along the diameter in the region M having a unit area determined by the F-number of the imaging lens is desirably 15 or less. Thereby, the imaging device 100 capable of recording a higher quality image can be obtained.

  In order to make the light refracted by the refracting surface 212 accurately enter the adjacent light receiving element 101, in addition to controlling the direction and angle of the refracting surface 212 of the prism element 201, the imaging element 111 and the prism group 110 are aligned. There is a need to. The holding unit 112 holds the image sensor 111 and the prism group 110 so that both are substantially perpendicular to the optical axis AX. The holding unit 112 fixes the distance L between the image sensor 111 and the prism group 110. By providing the holding portion 112 in this manner, the adjacent light receiving element 101 can be accurately incident on the incident light Lin refracted by the refractive surface 212. Thereby, there exists an effect that a moire can be reduced effectively. Note that the prism group 110 and the image sensor 111 are not limited to be positioned by the holding unit 112, and may be positioned by molding the prism group 110 and the image sensor 111 using, for example, a mold resin.

  Moire is likely to occur when the structure of the imaging apparatus 100 and the pattern of the subject OBJ overlap with the same period. It is conceivable that moiré occurs widely in the imaging apparatus 100 having a particularly small number of pixels. The prism group 110, which is a low-pass filter, is effective in reducing moiré, particularly when used in the imaging device 100 having a small number of pixels.

  The prism group 110 that is a low-pass filter may be provided at the pupil position of the imaging lens 1120 as shown in FIG. The pupil position is a conjugate position of the stop of the imaging lens 1120. The pupil position of the imaging lens 1120 has the highest light beam density. In other words, the light beam diameter is smallest at the pupil position. Therefore, when the prism group 110 is arranged at the pupil position, the size of the prism group 110 can be reduced. If the size of the prism group 110 can be reduced, the light can be effectively made uniform by passing a large amount of light through each prism element, and moire can be effectively eliminated.

  Further, if the prism group 110 can be made smaller, the imaging lens 1120 itself including the prism group 110 can also be made smaller. The prism group 110 can be easily manufactured and processed with high processing accuracy. Thereby, the imaging device 100 can be made small and inexpensive. The prism group 110 is not limited to the pupil position, and may be provided in the vicinity of the pupil position, a position conjugate to the pupil position, and a position in the vicinity thereof.

Next, the prism group manufacturing method will be described by taking the prism group 110 as an example. The prism group 110 is formed integrally with the transparent plate. The transparent plate is a transparent parallel plate glass. A prism group 110 is formed on one surface of the parallel plate glass by photolithography. Specifically, the photoresist layer is patterned on a parallel plate glass so as to have a desired prism shape, for example, a quadrangular pyramid shape, using a gray scale method to form a mask. Then, the prism group 110 is formed by an RIE (reactive ion etching) method using a fluorine-based gas such as CHF ₃ . The prism group 110 can also be formed by a wet etching method using hydrofluoric acid. Through this process, the flat portion and the refracting portion of the prism element 201 can be formed with high accuracy.

  Further, another method for manufacturing the prism group 110 will be described. The prism group 110 has a refractive surface angle of about 0.02 deg to 4.95 deg, and the height of the prism element 201 is about 0.01 to 2.5 μm. In order to create the prism group 110 having a fine structure by machining, high-precision machining is required for both the height of the prism element 201 and the angle of the refractive surface. When performing high-precision processing, a first flat portion forming step of forming the first flat portion by the cutting portion, and the first flat portion is cut by a predetermined depth by the cutting portion, and the first flat portion is cut. A second refractive surface processing step that forms a predetermined angle can be used. At this time, the flat portion can be formed at a plurality of height positions by subsequently performing the second flat portion forming step.

  In addition, in a trial machining area different from the first flat part, a trial machining process for forming a predetermined shape by the cutting part based on machining data, a shape measurement process for measuring the predetermined shape formed in the trial machining process, and a shape measurement A feedback process for correcting the machining data by feeding back the difference between the measurement data obtained in the process and the machining data to the machining data, and a first flat portion forming process and a second refractive surface forming process based on the corrected machining data. Therefore, a desired shape can be formed. Furthermore, a flat portion or a refracting surface may be formed by a third processing step.

  When performing these processes, it is desirable not to reattach the tool or rechuck the object to be processed, and to keep the relative relationship between the tool, the object to be processed, and the processing machine in a series of processes constant. Moreover, it can manufacture in large quantities cheaply by using what was obtained with this process target object as a metal mold | die, and shaping using resin, such as PMMA, ZEONEX, Arton, and PC. Further, the mold can be made at a lower cost by compounding the mold by electroforming plating.

Furthermore, another manufacturing method of the prism group 110 will be described. Optical epoxy resin is applied to one side of the parallel plate glass. Next, a mold having a pattern in which irregularities are reversed from a desired prism shape is prepared. Then, the mold is transferred by pressing the mold against the epoxy resin. Finally, the optical epoxy resin is irradiated with ultraviolet rays and cured to form the prism group 110. In addition, other methods can be employed for mold transfer. The parallel plate glass is heated and softened to the extent necessary for mold transfer. Then, the above-described mold is pressed onto one surface of the softened parallel plate glass to perform mold transfer. This also allows the prism group 110 to be formed on the parallel plate glass.

  The prism group 110 is not limited to being formed integrally with the transparent plate. For example, a prism group 110 having a desired prism shape is separately manufactured as a pattern sheet by a hot press method. Then, the pattern sheet is cut into a required size. Next, the cut pattern sheet is attached to the exit surface side of the parallel plate glass using an optically transparent adhesive. This also allows the prism group 110 to be formed on the parallel plate glass.

  More preferably, it is desirable to prevent dust and the like from adhering to the surface of the prism group 110. For this purpose, a coating layer made of a transparent resin having a low refractive index is formed on the exit side surface of the prism group 110. For example, the prism group 110 is formed of an optical epoxy high refractive index resin having a refractive index n = 1.56. The coating layer is formed of, for example, an optical epoxy low refractive index resin having a refractive index n = 1.38. Moreover, the refractive index of the member which comprises the prism group 110, and the refractive index of a coating layer can also be made to correspond substantially. Thereby, it is possible to reduce the occurrence of positional deviation of the refracted light on the image sensor 111 due to variations in manufacturing errors of the refractive surface 212.

  12-1 to 12-6 show examples of various variations of the shape of the prism elements. For example, FIG. 12A shows a prism group 1210 in which trapezoidal prism elements each having a refractive surface 1210a and a flat portion 1210b are provided at a predetermined interval. FIG. 12-2 shows a prism group 1220 having a refracting surface 1220a and a flat portion 1220b, in which trapezoidal prism elements are provided without gaps. FIG. 12-3 shows a prism group 1230 having a refracting surface 1230a and a flat portion 1230b, and triangular prism elements provided at predetermined intervals. FIG. 12-4 shows a blazed prism group 1240 consisting only of the refractive surface 1240a.

  FIG. 12-5 shows a prism group 1250 having a refracting surface 1205a and a flat portion 1250b, where the position of the refracting surface 1205a and the height of the flat portion 1250b are random. FIG. 12-6 shows a prism group 1260 having a refracting surface 1206a and a flat portion 1250b, the position of the refracting surface 1206a is random, and the height of the flat portion 1250b is substantially constant. Since both the prism groups 1250 and 1260 have an aperiodic configuration, the occurrence of diffraction can be reduced and the recorded image can be made high contrast. As described above, various variations can be made using the direction of the refracting surface, the inclination angle, and the area as parameters.

  Furthermore, the prism group having a configuration capable of reducing the occurrence of diffraction is not limited to the non-periodic configuration shown in FIGS. 12-5 and 12-6, and a combination of a plurality of prism elements having different shapes can be combined. May be formed repeatedly. The imaging apparatus 100 can record a high-contrast image by using a prism group configured to reduce the occurrence of diffraction.

  FIG. 13 shows a modification of the prism element. The prism element 1311 shown in FIG. 13 has a substantially square shape. The prism element 1311 has quadrangular pyramid-shaped refracting surfaces 1312a, 1312, 1312c, and 1312d. A flat portion 1313 is provided around the refracting surfaces 1312a, 1312b, 1312c, and 1312d. The light transmitted through the flat portion 1313 directly forms a transmission image. Then, an image is formed at an oblique position by each of the refractive surfaces 1312a, 1312b, 1312c, and 1312d. By forming a new image in this way, the apparent resolution can be improved 1.25 times in a pseudo manner.

  The prism element 1311 has a unit area T. Each refracting surface 1312a, 1312b, 1312c, 1312d has an area T / 8, and the flat portion 1313 has an area 4T / 8. In this case, in the image sensor 111, the light amount of the directly transmitted image is proportional to 4T / 8 = T / 2. Further, the amount of light forming a new image is proportional to 4 × (T / 8) = T / 2. In this way, by controlling the area of each surface of the prism element 1311, the brightness of each image can be arbitrarily made, for example, substantially the same. Thereby, the periodicity of the image of the subject OBJ can be reduced. The prism element is not limited to a quadrangular pyramid-shaped refracting surface, but may be provided with another polygonal pyramid-shaped refracting surface according to the number of images to be divided.

  FIG. 14 shows another modification of the prism element. The prism element 1411 shown in FIG. 14 has a substantially square shape. The prism element 1411 has quadrangular pyramid-shaped refracting surfaces 1412a, 1412b, 1412c, and 1412d. Note that, unlike the prism element 1311 shown in FIG. 13, no flat portion is formed. By not providing the flat portion, the prism element 1411 does not form an image by directly transmitting light. Each refraction surface 1412a, 1412b, 1412c, 1412d forms four images. All four images are formed without overlapping.

  The prism element 1411 has a unit area T. Each refracting surface 1412a, 1412b, 1412c, 1412d has an area T / 4. In this case, in the image sensor 111, each image can be made equal to each other and have a light amount proportional to the area T / 4. Thereby, the periodicity of the image of the subject OBJ can be further reduced. The prism element is not limited to a quadrangular pyramid-shaped refracting surface, but may be provided with another polygonal pyramid-shaped refracting surface according to the number of images to be divided.

  FIG. 15 shows a schematic configuration in which a part of a prism group according to a modification is enlarged. The prism group 1500 includes a first prism element 1510 having a quadrangular pyramid shape and a second prism element 1520 having a quadrangular pyramid shape. The first prism element 1510 is formed so that one side thereof forms approximately 45 ° with respect to the two directions in which the light receiving elements 101 are arranged. The second prism element 1520 is formed so that the side is substantially parallel to any of the two directions in which the light receiving elements 101 are arranged. Further, a flat portion 1530 is provided around the first prism element 1510 and the second prism element 1520.

  Thus, by arranging the prism elements at random, the diffraction effect can be suppressed and a high-contrast recorded image can be obtained. Further, the shape of the prism element is not limited to a quadrangular pyramid shape, and any shape having a refractive surface in a desired direction may be used. For example, a polygonal pyramid shape such as a hexagonal pyramid or an octagonal pyramid, or a trapezoidal shape obtained by cutting the polygonal pyramid shape may be used. The same effect can be obtained regardless of whether the projection direction of the optical element is convex or concave with respect to the outer shape of the prism element.

  The prism group 1500 forms an image with light directly transmitted through the flat portion 1530. The first prism element 1510 forms an image in a direction of 45 ° with respect to the two directions in which the light receiving elements 101 are arranged, by the refractive surface 1511. The second prism element 1520 forms an image in two directions in which the light receiving elements 101 are arranged by the refractive surface 1521. Various modifications can be made to the shape of the prism group that causes the same refraction action as in this modification. For example, a prism group 1600 having a refracting surface 1610 and a flat portion 1620 as shown in FIG. 16 can be used.

  FIG. 17 illustrates an image formed on the image sensor 111 by the prism groups 1500 and 1600. The prism groups 1500 and 1600 form an image on one light receiving element 101 by light transmitted through the flat portion. In addition, the prism groups 1500 and 1600 form eight images by light transmitted through the refractive surface. The eight images are formed on the eight light receiving elements 101 adjacent to the light receiving element 101 on which the light transmitted through the flat portion is incident. In this way, the prism groups 1500 and 1600 divide the image of the subject OBJ into nine images PI1 to PI9.

  The prism groups 1500 and 1600 set the direction of the refracting surface and the inclination angle so that the light transmitted through the prism elements 1510 and 1520 forms an image on the adjacent light receiving element 101. For example, in the prism group 1500, the area ratio of the refracting surfaces is set to the unit area T as the area T / 16 of the refracting surface 1511, the area 2T / 16 of the refracting surface 1521, and the area 4T / 16 of the flat portion 1530. As a result, images can be formed with substantially the same amount of light.

  The prism group may be configured to divide the image of the subject OBJ into more images. For example, as shown in FIG. 18, the image of the subject OBJ may be divided into 13 images PI1-13. Thereby, the periodicity of the image of the subject OBJ can be further reduced, and the occurrence of moire can be reduced. Thus, by increasing the number of refracting surfaces in different directions, a high-quality image can be easily recorded.

  FIG. 19 shows a schematic perspective configuration of a prism group 1900 that is a low-pass filter according to Embodiment 2 of the present invention. The prism group 1900 can be applied to the imaging device 100 of the first embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The prism group 1900 includes two sets of prism elements 1910a and 1910b.

  The prism element 1910a has a substantially trapezoidal cross-sectional shape in the y-axis direction, which is the first direction. The prism element 1910a has a longitudinal direction in the x-axis direction, which is the second direction substantially perpendicular to the y-axis direction, which is the first direction. Of the trapezoidal shape having a cross-sectional shape in the y-axis direction of the prism element 1910a, the two inclined surfaces Y1 and Y2 function as refractive surfaces. Of the cross-sectional shape of the prism element 1910a in the y-axis direction, the upper surface Y0 functions as a flat portion. For this reason, the light incident on the slope Y1 or the slope Y2 is refracted in a direction corresponding to the angle of the slope. A refracted transmission image is formed by the refracted light. Further, the light incident on the upper surface Y0 is transmitted as it is. A direct transmission image is formed by the light transmitted as it is.

  The prism element 1910b has the same configuration as the prism element 1910a. Of the cross-sectional shape of the prism element 1910b in the x-axis direction, the two inclined surfaces X1 and X2 function as refractive surfaces. Of the cross-sectional shape of the prism element 1910b in the x-axis direction, the upper surface X0 functions as a flat portion. The two sets of prism elements 1910a and 1910b are provided such that their longitudinal directions are substantially orthogonal to each other.

Further, in this embodiment, the plane side of the prism element 1910a and the plane side of the prism element 1910b are fixed facing each other. However, it is not limited to this, and any one of the following configurations (1) to (3) may be used.
(1) A configuration in which the surface of the prism element 1910a on which the inclined surfaces Y1, Y2, etc. are formed and the surface of the prism element 1910b on which the inclined surfaces X1, X2, etc. are formed face each other and are fixed.
(2) A configuration in which the surface of the prism element 1910a on which the inclined surfaces Y1, Y2, etc. are formed and the flat surface side of the prism element 1910b face each other and are fixed.
(3) A configuration in which the flat surface side of the prism element 1910a and the surface on which the inclined surfaces X1, X2, etc. of the prism element 1910b are formed face each other and are fixed.
In addition, although the structure which a prism surface touches is shown in FIG. 19, the structure which both surfaces contact with air may be sufficient.

  FIG. 20 shows the splitting of incident light by the prism group 1900. In FIG. 20, incident light XY travels from the left side toward the right side. In addition, in a part of FIG. 20, for convenience of explanation, the light beam is specified using the symbols of the slopes Y0, Y1, and Y2. Incident light XY is split into three light beams, a light beam Y1 and Y2 refracted on the slope and a light beam Y0 that passes through the upper surface as it is, by a prism element 1910a indicated by a dotted line. The branched three light beams Y0, Y1, and Y2 are further branched into three light beams by the prism element 1910b. Incident light XY is branched into nine light beams Y1X1, Y1X0, Y1X2, Y0X1, Y0X0, Y0X2, Y2X1, Y2X0, and Y2X2.

  The prism group 1900 can form nine images as shown in FIG. 17 by branching incident light into nine light beams as in the case of the prism groups 1500 and 1600 described above. The prism group 1900 sets the direction and the inclination angle of the slope so that an image is formed on the adjacent light receiving element 101 by the light transmitted through the slope of each prism element 1910a, 1910b. As a result, it is possible to effectively reduce moiré and to record a high-quality image with a small and inexpensive configuration. The prism group 1900 can be easily manufactured by bonding the prism elements 1910a and 1910b formed by using a molding technique or the like in the same manner as the prism group 110 of the first embodiment.

  FIG. 21 shows a schematic configuration of a camera-equipped cellular phone 2100 that is an electronic apparatus according to Embodiment 3 of the present invention. The camera-equipped mobile phone 2100 includes a camera unit 2120 that is an imaging device. The camera-equipped mobile phone 2100 stores the image of the subject by turning the shutter with the imaging lens of the camera unit 2120 facing the subject. The imaging apparatus has a feature that moire can be reduced with a small configuration. In addition, an imaging apparatus having a relatively small number of pixels has a property that moire is likely to occur widely. The camera-equipped mobile phone 2100 is required to have a small, thin, and lightweight configuration, and the number of pixels of the camera portion 2120 is relatively small. Therefore, the image pickup apparatus of the above embodiment is suitable for application to the camera-equipped mobile phone 2100. By using the imaging device of the above embodiment as the camera unit 2120, moire can be effectively reduced with a small and inexpensive configuration. Note that the camera-equipped mobile phone 2100 may be either one that can shoot a still image or one that can shoot a moving image in addition to a still image.

  FIG. 22 shows a schematic perspective configuration of a digital video camera 2200 which is another electronic apparatus according to the third embodiment. The digital video camera 2200 includes a camera unit 2220 that is an imaging device. When the digital video camera 2200 is in a recording state, the digital video camera 2200 stores images of the subject to which the imaging lens of the camera unit 2220 is directed in time series. Many digital video cameras 2200 have a number of pixels with a period at which moiré is relatively likely to occur. The digital video camera 2200 is also required to have a small and lightweight configuration. Therefore, the imaging apparatus of the above embodiment is suitable for application to the digital video camera 2200. By using the imaging device of the above embodiment as the camera unit 2220, moire can be effectively reduced with a small and inexpensive configuration.

  The image pickup apparatus of the present invention is not limited to the camera-equipped mobile phone 2100 and the digital video camera 2200, but is applied to electronic devices having a photographing function, for example, other portable information devices such as PDAs and personal computers, digital still cameras, and video phones. Can be used widely.

  As described above, the imaging apparatus according to the present invention is useful when storing still images and moving images.

1 is a schematic configuration diagram of an imaging apparatus according to Embodiment 1 of the present invention. The perspective block diagram of a prism group. Explanatory drawing of behavior of incident light. The top view of a prism group. The top view of a prism group. The enlarged view of the prism group vicinity. Explanatory drawing of the light condensed on one point on an image plane. Explanatory drawing of the light which passes one point on a prism group. The layout of a light receiving element. Explanatory drawing of the image formed in an image sensor. The schematic block diagram of the imaging lens which has arrange | positioned the prism group in the pupil position. The cross-sectional block diagram of the variation of a prism group. The cross-sectional block diagram of the variation of a prism group. The cross-sectional block diagram of the variation of a prism group. The cross-sectional block diagram of the variation of a prism group. The cross-sectional block diagram of the variation of a prism group. The cross-sectional block diagram of the variation of a prism group. The top view of the prism element which concerns on a modification. The top view of the prism element which concerns on a modification. The partial top view of the prism group which concerns on a modification. The partial top view of the prism group which concerns on a modification. Explanatory drawing of the image formed on an image sensor. Explanatory drawing of the image formed on an image sensor. The schematic perspective block diagram of the prism group which concerns on Example 2 of this invention. Explanatory drawing of the branching of the incident light by a prism group. FIG. 10 is a schematic configuration diagram of an electronic apparatus according to a third embodiment of the invention. FIG. 6 is a schematic configuration diagram of another electronic device according to a third embodiment of the invention. The figure which shows the structural example of the prism group which can reduce the influence of a diffracted light. The figure which shows the structural example of the prism group which can reduce the influence of a diffracted light.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Image pick-up device, 101 Light receiving element, 103 Light-shielding part, 104 Color filter, 105 Color filter layer, 106 Micro lens array, 107 Infrared cut filter, 110 Prism group, 111 Image sensor, 112 Holding part, 113, 114 Fixed surface, 120 Imaging lens, 201 prism element, OBJ subject, SA, SB refracting surface, SC flat portion, 211a side portion, 212, 212a, 212b, 212c, 212d refracting surface, 213 flat portion, 213a reference surface, PI1-5 image, 1120 Imaging lens, 1210, 1220, 1230, 1240, 1250, 1260 Prism group, 1210a, 1220a, 1230a, 1240a, 1250a, 1260a Refractive surface, 1210b, 1220b, 1230b, 1250b, 126 b Flat part, 1311 Prism element, 1312a, 1312b, 1312c, 1312d Refraction surface, 1313 Flat part, 1411 Prism element, 1412a, 1412b, 1412c, 1412d Refraction surface, 1500 Prism group, 1510, 1520 Prism element, 1511, 1521 Refraction Surface, 1530 flat part, 1600 prism group, 1610 refractive surface, 1620 flat part, PI1-9, PI1-13 image, 1900 prism group, 1910a, 1910b prism element, 2100 mobile phone with camera, 2120 camera part, 2200 digital video Camera, 2220 Camera unit, 2310 Prism group, 2311 First prism element, 2312 Second prism element, 2313 Edge, 2320 Prism group, 2321 Priz Element, 2323 edge

Claims (10)

An image sensor comprising a plurality of light receiving elements arranged in a matrix and converting incident light into an image signal;
A low pass filter provided on the incident side of the image sensor,
The low-pass filter has a prism group composed of prism elements having at least a refractive surface,
The refracting surface refracts the incident light in a predetermined direction.   The refracting surface is substantially oriented with respect to the direction in which the incident light is guided to the light receiving element adjacent to the light receiving element at the incident position when the incident light travels straight through the prism group, and with respect to the refractive surface and the optical axis. The imaging apparatus according to claim 1, wherein the imaging apparatus has an angle with a reference plane formed in a vertical direction. The prism group includes two sets of prism elements each having a substantially trapezoidal cross-sectional shape in a first direction and having a longitudinal direction in a second direction substantially orthogonal to the first direction;
The two sets of prism elements are provided so that the longitudinal directions thereof are substantially orthogonal to each other,
The imaging apparatus according to claim 1, wherein the trapezoidal slope corresponds to the refractive surface. The prism element has at least four refracting surfaces;
The imaging apparatus according to claim 1, wherein the refracting surfaces have different directions.   The prism group includes at least a first prism element having a first shape and a second prism element having a second shape different from the first shape. The imaging apparatus as described in any one of -4. An imaging lens for guiding the incident light to the imaging device;
The imaging apparatus according to claim 1, wherein the prism group is provided in an optical path between the imaging lens and the imaging element. An imaging lens for guiding the incident light to the imaging device;
The prism group is provided at a pupil position of the imaging lens, a position conjugate to the pupil position, a vicinity of the pupil position, or a vicinity of the conjugate position. The imaging device according to item.   In a substantially circular region having a unit area determined by the F-number of the imaging lens, the number of edges of the boundary of the prism elements substantially perpendicular to a straight line along the diameter of the substantially circular shape is 50 or less. The imaging apparatus according to claim 6 or 7, characterized by the above.   The holding unit that holds the prism group at a predetermined position with respect to the position of the image pickup element by fixing the image pickup element and the prism group. The imaging device described in 1.   An electronic apparatus comprising the imaging device according to claim 1.

Images