JP2017156565A - Lens sheet, image capturing module, and image capturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens sheet that does not require an imaging lens even when an optical system comprising a group of microlens elements is used.SOLUTION: A lens sheet (21, 31) comprises light transmissive sections (22) configured to extend in one direction along a sheet surface and arrayed at a predetermined pitch in a direction different from the extending direction; a light absorptive section (23) formed between each pair of adjacent light transmissive sections and designed to absorb light; a convex-shaped unit convex lens element (24) provided on each light transmissive section; and concave-shaped unit concave lens elements (26) provided on an opposite side across the light transmissive sections.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a lens sheet, an imaging module, and an imaging apparatus that can acquire depth information of a subject together with a two-dimensional image.

  In recent years, due to the mounting of cameras on mobile terminals such as smartphones and tablets, and the demand for small cameras that can be worn, there has been a demand for downsizing of cameras, in particular, reduction in thickness of the camera part.

  For example, Patent Document 1 discloses a technique related to an imaging device having an imaging lens, a microlens array, and a photoelectric conversion sensor. This is called a light field camera, etc., which divides incident light with a microlens array and shoots light in multiple directions, and performs image processing based on the incident direction and intensity of light after shooting. The focal length and depth of field can be changed. That is, this image can also include information in the depth direction, and the image can be focused at an arbitrary position and range within a predetermined range after being imaged. Accordingly, the focus can be achieved without using the autofocus function, and since the information in the depth direction is included, the relative distance can also be measured.

Special table 2015-520992 gazette

  Here, the above-described imaging apparatus has a microlens array and a photoelectric conversion sensor, and each sensor included therein determines which microlens the light should be received from. Therefore, if the sensor receives light from an unplanned microlens, image multiplexing occurs. In contrast, conventionally, an image forming optical system (image forming lens) is arranged on the light incident side of the micro lens array to control light, thereby preventing image multiplexing.

  However, if the imaging lens is arranged in this way, the imaging device tends to be thick, and there is a limit to reducing the thickness.

  In view of the above problems, an object of the present invention is to provide a lens sheet that does not require an imaging lens even when an optical system including a minute lens element group is used. In addition, an imaging module and an imaging apparatus including the same are provided.

  The present invention will be described below. Here, for ease of understanding, reference numerals attached to the drawings are described in parentheses, but the present invention is not limited thereto.

  The invention according to claim 1 is a lens sheet (20, 120, 220, 320) disposed on the light receiving surface side of the image sensor, and has a predetermined cross section and extends in one direction along the sheet surface. A plurality of light transmission parts (22) arranged at predetermined intervals in a direction different from the extending direction, a light absorption part (23) formed at an interval between adjacent light transmission parts, and a light transmission part Comprising a sheet (21, 31) comprising a convex unit convex lens element (24) provided on the concave side and a concave unit concave lens element (26) provided on the opposite side across the light transmission part, It is a lens sheet.

  According to a second aspect of the present invention, in the lens sheet (20) according to the first aspect, at least two sheets (21, 31) are stacked, and the two sheets extend in the direction in which the light transmitting portion (22) extends. Intersect in plan view.

  The invention according to claim 3 is the lens sheet (20) according to claim 1 or 2, and an image sensor (11) arranged on one side of the lens sheet, in which a plurality of photoelectric conversion elements are arranged, It is an imaging module (10) provided with.

  According to a fourth aspect of the present invention, in the imaging module according to the third aspect, the lens sheet (21) is such that the unit convex lens element (24) is disposed on the side opposite to the side where the image sensor (11) is disposed. 31) are installed.

  A fifth aspect of the present invention is an imaging apparatus (1) in which the imaging module (20) according to the third or fourth aspect is disposed inside the housing (2).

  According to the present invention, even when an optical system including a minute lens element group is used, generation of multiple images can be prevented without requiring an imaging lens. At that time, lens aberration can be corrected, and a more accurate image can be obtained.

1 is an external view of an imaging device 1. FIG. 2 is a diagram illustrating the structure of an imaging module 10. FIG. 2 is a perspective view of a lens sheet 20. FIG. FIG. 3 is a diagram illustrating the structure of a first sheet 21. It is a figure showing the one scene which produces the lens sheet. 6A is a perspective view of the lens sheet 120, and FIG. 6B is a perspective view of the lens sheet 220. 3 is a perspective view of a lens sheet 320. FIG. FIG. 8A shows an example of imaging in the present invention, and FIG. 8B shows an example of imaging that causes a problem.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings. However, the present invention is not limited to these forms. In the drawings, the size and shape of each part may be schematically modified or exaggerated for easy understanding. For ease of viewing, repeated symbols may be omitted.

  FIG. 1 is a diagram for explaining one embodiment, and is a diagram in plan view of a portable terminal 1 that is an imaging apparatus 1 including an imaging module 10. Thus, the imaging module 10 can be mounted on a portable terminal, a personal computer, a small camera, or the like to form an imaging device. In the case of this embodiment, a window is provided on the side shown in FIG. 1, light is taken into the imaging module 10 from here, and the imaging module 10 is operated on the opposite screen. Therefore, the imaging module 10 is arranged by being incorporated in the housing 2 constituting the portable terminal 1.

  FIG. 2 is a conceptual cross-sectional view illustrating the configuration of the imaging module 10. As can be seen from FIG. 2, the imaging module 10 includes a lens sheet 20, an image sensor 11, and image processing means 12.

  The lens sheet 20 is an optical element that includes a plurality of microlens elements, decomposes incident light into light beam groups to be collected on the image sensor 11, and outputs the light to the image sensor 11. In FIG. 2, one cross section of the lens sheet 20 appears. FIG. 3 shows a perspective view of a part of the lens sheet 20. Furthermore, FIG. 4 shows a diagram for explaining the structure of the lens sheet 20 by enlarging a part of FIG. As can be seen from FIGS. 2 and 3, in the lens sheet 20 of the present embodiment, the sheet-like first sheet 21 and the sheet-like second sheet 31 are arranged so as to overlap each other.

  In the first sheet 21, the light transmitting portions 22 and the light absorbing portions 23 are alternately arranged along the direction parallel to the sheet-like surface, and the unit convex lens element 24 is provided on one surface of the light transmitting portion 22. The unit concave lens element 26 is provided on the other side. As can be seen from FIG. 3, the first sheet 21 has the cross section shown in FIGS. 2 and 4 and extends to the back / near side of the drawing, and includes a light transmitting portion 22, a light absorbing portion 23, and a unit convex lens element. 24 and the unit concave lens element 26 are both columnar. That is, in the cross section shown in FIGS. 2 and 4, the first sheet 21 includes a light transmission part 22 that is substantially trapezoidal or rectangular, and a light absorption part 23 formed between two adjacent light transmission parts 22, The light transmitting portion 22 has a unit convex lens element 24 having a convex lens shape in cross section on one surface and a unit concave lens element 26 having a concave lens shape in cross section on the other surface.

The light transmission part 22 is a part whose main function is to transmit light. In this embodiment, in the cross section shown in FIGS. 2 and 4, a long lower bottom on one sheet surface side and the other on the opposite side. It is an element having a substantially trapezoidal shape having a short upper base on the sheet surface side, or a rectangular cross-sectional shape. The light transmission parts 22 extend in the above-described direction while maintaining the cross section along the sheet surface direction, and are arranged at predetermined intervals in a direction different from the extending direction. A groove-like interval having a substantially trapezoidal cross section or a rectangular cross section is formed between adjacent light transmission portions 22. Therefore, when the light transmission part 22 has a trapezoidal cross section, the interval is a trapezoidal cross section having a long lower base on the upper base side of the light transmission part 22 and a short upper base on the lower base side of the light transmission part 22. It becomes. And the light absorption part 23 is formed by being filled with a required material in the groove-shaped space | interval of this trapezoidal cross section or a rectangular cross section.
In the present embodiment, the adjacent light transmission parts 22 are connected on the long bottom side to form the base part 25. Therefore, in this embodiment, the base portion 25 forms the bottom of the groove (light absorption portion 23). The base portion 25 is preferably as thin as possible. Thereby, stray light can be suppressed and high image quality can be obtained.

  The light transmission portion 22 has a refractive index of Nt. The value of the refractive index Nt is not particularly limited, but the refractive index Nt is preferably 1.38 or more and 1.60 or less. A material having a refractive index smaller than 1.38 may cause a problem in availability, and if the refractive index is larger than 1.60, the material is likely to be cracked in many cases.

  Such a light transmission part 22 can be formed of, for example, an ultraviolet curable resin such as urethane acrylate, polyester allylate, or epoxy acrylate, an electron beam curable resin, or a thermoplastic resin such as polyethylene terephthalate (PET).

The light absorbing portion 23 is a portion that absorbs light provided between the adjacent light transmitting portions 22 provided at the above-described intervals. Therefore, when the light transmission part 22 has a trapezoidal cross section, the light absorption part 23 also has a trapezoidal cross section, the short upper bottom of the light absorption part 23 faces the lower bottom side of the light transmission part 22, and the long lower bottom of the light absorption part 23 It becomes the upper base side of the light transmission part 22. And the light absorption part 23 is comprised so that light can be absorbed while the refractive index is set to Nr. Specifically, light absorbing particles are dispersed in a binder having a refractive index of Nr. The refractive index Nr is preferably a refractive index equal to or higher than the refractive index Nt of the light transmitting portion 22. As described above, by setting the refractive index of the light absorbing portion 23 to be equal to or higher than the refractive index of the light transmitting portion 22, the light is not totally reflected at the interface between the light transmitting portion 22 and the light absorbing portion 23, and the light enters the light absorbing portion 23. Enter and can absorb light properly.
The value of the refractive index Nr is not particularly limited, and can be considered in the same manner as the light transmission portion 22.

  Although the material used as a binder is not specifically limited, For example, photocurable resin compositions, such as urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, and butadiene (meth) acrylate, can be mentioned. .

  The light absorbing particles used in this embodiment are composed of resin fine particles and a color material layer covering the surface of the resin fine particles.

As the resin fine particles, melamine beads, acrylic beads, acrylic-styrene beads, polycarbonate beads, polyethylene beads, polystyrene beads, polyvinyl chloride beads and the like can be used without particular limitation. Among these, an acrylic cross-linked polymer, a styrene cross-linked polymer, or an acrylic-styrene copolymer can be preferably used.
The resin fine particles may be transparent, but it is preferable to use a resin colored with a pigment or a dye, which may selectively absorb a specific wavelength as necessary, but preferably black. Colored resin fine particles are used.

The color material that constitutes the color material layer and covers the surface of the resin fine particles can be used without particular limitation as long as it absorbs light, and includes a colored filler and carbon black. it can.
As the colored filler, for example, a colored filler in which a pigment is dispersed in a polymer can be suitably used. For example, a resin obtained by adding a pigment to a monomer such as methyl methacrylate or styrene and polymerizing it can be used. It can be preferably used. As the pigment, known organic pigments and inorganic pigments can be used. For example, inorganic black pigments such as carbon black, aniline black, perylene black, and inorganic pigments containing copper, iron, chromium, manganese, cobalt, etc. A black pigment, titanium black, or the like can be preferably used.
Carbon black having an average particle diameter of 10 nm to 500 nm can be suitably used. For example, furnace black, acetylene black, channel black, thermal black, carbon nanotube, carbon fiber, and the like can be used. Commercially available products can also be used. For example, HCF series, MCF series, RCF series, LFF series (all manufactured by Mitsubishi Chemical Corporation), Vulcan series (made by Cabot Corporation), Ketjen series (Lion Corporation) Etc.) can be preferably used.

Here, the light-absorbing particles of this embodiment preferably have an average particle diameter of 1 μm or more and 5 μm or less. When the average particle diameter is smaller than 1 μm, there is a high possibility that the light absorbing particles remain on the surface of the light transmission part when a lens sheet is manufactured using wiping described later. On the other hand, if the average particle diameter is larger than 5 μm, it becomes difficult to fill the space between the light transmission parts, and there is a possibility that sufficient light absorption cannot be obtained.
Here, the “average particle diameter” means an arithmetic average diameter obtained by observing 100 light absorbing particles with an electron microscope and measuring the diameter.

Moreover, it is preferable that the ratio of the mass part of a binder and light absorption particle | grains is 10-20 mass parts of light absorption particles with respect to 100 mass parts of binders. If the amount is less than 10 parts by mass, the light absorption performance may be insufficient. If the amount is more than 20 parts by mass, light absorbing particles remain on the surface of the light transmission part when a lens sheet is manufactured using wiping described later. There is a high possibility that In addition, when the binder is an ultraviolet curable resin, there are many light absorbing particles, the progress of the ultraviolet curing reaction is hindered, and the possibility that the light absorbing portion is not sufficiently cured increases.
Accordingly, the optical density of the light-absorbing particles is preferably 2.4 or more and 4.7 or less from the viewpoint of light absorption.

In this embodiment, an example in which the interface (leg part of the trapezoidal cross section) between the light transmitting part 22 and the light absorbing part 23 is straight in the cross section is shown, but not limited to this, it is a polygonal line, a convex curved surface, or a concave It may be a certain curved surface. Moreover, the cross-sectional shape may be the same in the some light transmissive part 22 and the light absorption part 23, and a different cross-sectional shape may have predetermined regularity as needed.
Further, the cross section is not necessarily an isosceles trapezoid, and one leg and the other leg are not line-symmetric, and one and the other may be configured such that the inclination angle and shape are different.

Next, the unit convex lens element 24 will be described. As can be seen from FIGS. 2 to 4, the unit convex lens element 24 has a convex shape having a curved portion in cross section in this embodiment, and has the cross section and extends in the same direction as the light transmitting portion 22. The light transmitting portion 22 and the unit convex lens element 24 are positioned so as to be in the same position when the lens sheet 20 is viewed from the front. In this embodiment, the unit convex lens element 24 is directly disposed on one surface of the light transmitting portion 22 and is integrated.
The unit convex lens element 24 of the first sheet 21 and the unit convex lens element 24 of the second sheet 31 control light so as to achieve the same effect as the microlens. That is, the light transmitted through the lens sheet 10 is condensed by the unit convex lens element 24 so as to be focused on the light receiving surface of the image sensor 11. Accordingly, the radius of curvature R and the refractive index of the unit convex lens element 24 are determined so that the light can be controlled in this way.
Therefore, the cross-sectional shape of the unit convex lens element 24 is not particularly limited, and may be a part of an ellipse, a circular arc, and a polygonal shape, or may be a shape in which these are combined.

  In addition, a layer having an antireflection function may be formed on the surface of the unit convex lens element 24. This layer can be formed by coating a material having an antireflection function such as magnesium fluoride, silicon dioxide, or a fluorine-based coating agent with a predetermined film thickness.

Next, the unit concave lens element 26 will be described. As can be seen from FIGS. 2 to 4, the unit concave lens element 26 has a concave shape having a curved portion in cross section, and has the same cross section and extends in the same direction as the light transmitting portion 22. The unit concave lens element 26 is disposed on the opposite side of the light transmitting portion 22 from the unit convex lens element 24. That is, in this embodiment, it is provided so as to be laminated on the base portion 25. The unit concave lens element 26 is positioned so as to be in the same position with respect to the light transmitting portion 22 and the unit convex lens element 24 when the lens sheet 20 is viewed from the front. Furthermore, the unit concave lens element 26 preferably has the same optical axis as the unit convex lens element 24.
Depending on the curvature and shape of the unit concave lens element 26 of the first sheet 21 and the unit concave lens element 26 of the second sheet 31, the control of the light by the unit convex lens 24 is assisted and the light is controlled to correct the lens aberration. That is, when the light transmitted through the lens sheet 10 is focused by the unit convex lens element 24 so as to be focused on the light receiving surface of the image sensor 11, the lens aberration of the unit concave lens element 26 can be corrected. A combination of curvature, shape, and curvature and shape of the unit convex lens element 24 is determined.
Therefore, the cross-sectional shape of the unit concave lens element 26 is not particularly limited, and may be a part of an ellipse, a circular arc, and a polygonal shape, or may be a shape in which these are combined. However, for imaging on the image sensor, it is necessary to adjust the curvature of the concave lens element and the convex lens element so that the entire combination becomes a convex lens.

  Also, a layer having an antireflection function may be formed on the surface of the unit concave lens element 26. This layer can be formed by coating a material having an antireflection function such as magnesium fluoride, silicon dioxide, or a fluorine-based coating agent with a predetermined film thickness.

Although the 1st sheet | seat 21 is not specifically limited, For example, the light transmissive part 22, the light absorption part 23, the unit convex lens element 24, and the unit concave lens element 26 are formed as follows. Symbols are given in FIG.
The arrangement pitch P of the light transmitting portion 22, the unit convex lens element 24, and the unit concave lens element 26 is preferably 20 μm or more and 180 μm or less. Therefore, the pitch of the light absorption part 23 is also the same.
At this time, the size D _{t in} the pitch direction (width direction) on the side where the unit convex lens element 24 is arranged in the light transmitting portion 22 is also the width of the unit convex lens element 24 and is larger than 20 μm and smaller than 180 μm. preferable. Similarly, the size W in the pitch direction (width direction) of the light absorbing portion 23 on the surface on which the unit convex lens element 24 is disposed is preferably 2 μm or more and 30 μm or less.
The size D _{O of} the unit concave lens element 26 in the width direction is preferably larger than 20 μm and smaller than 180 μm. When the width direction size Do of the unit concave lens elements 26 is smaller than the pitch of the unit concave lens elements 26, a flat portion 26a is formed between the adjacent unit concave lens elements 26 as shown in FIG.

On the other hand, the thickness T of the first sheet 21 is the distance from the top of the unit convex lens element 24 to the surface on the unit concave lens element 26 side, and is preferably 30 μm or more and 480 μm or less.
Among these, it is preferable that the thickness _{T 1} of the unit convex lens element 24 is 2μm or more 40μm or less. Further, it is preferable that the thickness _{T 2} of the light transmission portion 22, and the light absorbing portion 23 is 20μm or more 470μm or less.
The thickness T ₃ of the base portion 25 is preferably 1 μm or more and 50 μm or less. Thereby, it is possible to suppress stray light or light incident on the light transmission part 22 from proceeding to the other adjacent light transmission part 22 side.
The thickness T ₄ of the unit concave lens element 26 is preferably 2 μm or more and 40 μm or less.

Further, it is preferable that the curvature radius _{R t} of the unit convex lens element 24 is 10μm or more 180μm or less. Thereby, optical adhesion can be suppressed. If the radius of curvature _Rt is smaller than 10 μm, the optical effect as the unit convex lens element 24 (effect as a lens) cannot be obtained. Meanwhile curvature radius R _t is close to the flat shape is as large as the unit lens elements than 180 [mu] m, the optical contact is likely to occur.
On the other hand, the radius of curvature R _O of the unit concave lens element 26 is preferably 20 μm or more and 180 μm or less. In order to appropriately form an image on the imaging element, it is necessary to adjust the radius of curvature R _O of the concave lens to be larger than the radius of curvature R _t of the convex lens to be combined so that the entire lens sheet becomes a convex lens.
Furthermore, the angle θ formed by the interface between the light transmission part 22 and the light absorption part 23 and the sheet surface normal (thickness direction) is preferably 0 ° or more and 10 ° or less. At 0 degree, the light transmission part and the light absorption part are rectangular.

The first sheet 21 as described above can be produced, for example, as follows.
First, the light transmission part 22 and the unit convex lens element 24 are produced. The composition before the hardening which comprises the said light transmission part and a unit lens element is supplied to the surface of the metal mold | die which can transcribe | transfer the shape of a light transmission part and a unit convex lens element, and it is made to harden | cure by a suitable method, and is 1st Get an intermediate sheet. The first intermediate sheet is a sheet in which the light transmitting portion 22 and the unit convex lens elements 24 are arranged at a predetermined interval on one surface of the base portion 25, and a groove is formed by the interval.

  Next, a unit concave lens element 26 is formed on the side opposite to the unit convex lens element 24 with respect to the manufactured first intermediate sheet. This is because the composition before the curing constituting the unit concave lens element 26 is supplied between the mold capable of transferring the shape of the unit concave lens element and the first intermediate sheet, and cured by an appropriate method. A second intermediate sheet is obtained. The second intermediate sheet is a sheet in which unit concave lens elements 26 are arranged at a predetermined interval on the other surface of the base portion 25 with respect to the first intermediate sheet.

  Next, the light absorption part 23 is formed. FIG. 5 shows a diagram for explanation. As can be seen from FIG. 5, the composition 23 ″ constituting the light absorbing portion is excessively supplied to the groove 23 ′ between the plurality of light transmitting portions 22 and the unit convex lens elements 24, and is continuously applied by the doctor blade 100 or the wiping roll. (Sometimes referred to as wiping), the groove 23 ′ is reliably filled with the composition 23 ″ and the surplus is appropriately scraped off. And the light absorption part 23 is formed by hardening a binder by a suitable method.

  Thereby, the 1st sheet | seat 21 can be produced efficiently. Further, when the average particle diameter of the light-absorbing particles of the composition constituting the light-absorbing part and the content ratio of the light-absorbing particles with respect to the binder are defined as described above, the surface of the light-transmitting part 22 even if the scraping is performed It is possible to reliably prevent the light absorbing particles from remaining on the surface.

  Returning to FIG. 2 and FIG. 3, the second sheet 31 will be described. The structure of the second sheet 31 and the manufacturing method thereof are the same as those of the first sheet 21 described so far. Therefore, the description is omitted by using the same reference numerals as in FIG.

The first sheet 21 and the second sheet 31 as described above are combined into the lens sheet 20 as follows, for example.
As can be seen from FIGS. 2 and 3, the first sheet 21 and the second sheet 31 are arranged so that the unit convex lens elements 24 face each other, and the light transmitting portion 22 is seen in a plan view of the lens sheet 20. The direction in which the light absorbing portion 23, the unit convex lens element 24, and the unit concave lens element 26 extend intersects at an angle α (see FIG. 4). This embodiment is an example in which α is 90 degrees. However, α does not need to be exactly 90 degrees, and is allowed within a range of α ± 10 degrees. Within this range, the optical performance can be sufficiently maintained. Thereby, when the first sheet 21 and the second sheet 31 are combined, it is not necessary to strictly set α to 90 degrees, so that the work is facilitated, the work is highly efficient, and the yield is improved.

  In this embodiment, the unit convex lens element 24 of the first sheet 21 and the unit convex lens element 24 of the second sheet 31 are arranged so as to face each other. Configured to touch. However, the present invention is not limited to this, and a slight gap may be provided between the apexes.

The lens sheet 20 in which the unit convex lens element 24 of the first sheet 21 and the unit convex lens element 24 of the second sheet 31 face each other has been described as one form. However, the present invention is not limited to this, and other arrangements are possible. 6 and 7 are perspective views. These figures correspond to FIG.
In the lens sheet 120 according to the example of FIG. 6A, the unit convex lens element 24 of the first sheet 21 is disposed so as to face the unit concave lens element 26 of the second sheet 31.
In the lens sheet 220 according to the example of FIG. 6B, the unit convex lens element 24 of the second sheet 31 is disposed so as to face the unit concave lens element 26 of the first sheet 21. According to this example, since the light incident side surface is a unit convex lens element 24, the light that has passed through the convex lens first is collected and is difficult to reach the light absorbing portion 23. Light can be used efficiently.
In the lens sheet 320 according to the example of FIG. 7, the unit concave lens element 26 of the first sheet 21 and the unit concave lens element 26 of the second sheet 31 are arranged to face each other.

Returning to FIG. 2, the image sensor 11 will be described. The image sensor 11 is a sensor formed by arranging a plurality of so-called photoelectric conversion elements that convert light received by a light receiving surface into an electric signal and output the electric signal. In the image sensor 11, a plurality of elements are arranged in a two-dimensional direction, and the intensity of light incident on the elements can be detected by each element. Each element forms each pixel.
A plurality of elements constituting the image sensor 11 are arranged in a two-dimensional direction on the surface on the subject side (lens sheet 20 side) which is the light receiving surface of the image sensor 11.
Examples of the elements constituting such an image sensor 11 include a CCD and a CMOS.

  The image processing means 12 is means for receiving the electrical signal obtained by the image sensor 11 and performing image processing to generate depth information and the like. The image processing means 12 is formed of a so-called arithmetic board, is formed with a central operator (CPU), ROM, RAM, etc., and performs arithmetic operations with the central operator based on a program stored in the ROM. Perform image processing with.

  The lens sheet 20, the image sensor 11, and the image processing unit 12 as described above are combined into the imaging module 10 as follows, for example. That is, as shown in FIG. 2, the lens sheet 20 is arranged so that the first sheet 21 faces the subject on the left side of FIG. 2.

  Here, in plan view, the direction in which the elements of the image sensor 11 are arranged and the direction in which the light transmission part 22 of the first sheet 21 and the light transmission part 22 of the second sheet 31 extend coincide with each other or are orthogonal to each other. It is preferable. As a result, the element of the image sensor 11 and the pseudo microlens by the lens sheet 20 are accurately associated, and problems such as crosstalk are hardly caused. However, it is not necessarily strictly parallel or vertical, and a deviation of 10 degrees from the parallel or vertical is allowed. Within this range, the optical performance can be sufficiently maintained. Thereby, when the imaging module 10 is manufactured, the work is facilitated, the work efficiency is increased, and the yield is improved.

  The image sensor 11 and the image processing unit 12 are electrically connected to communicate data.

  In addition to the above, the imaging module 10 may be provided with an infrared shielding layer or an antireflection layer. As a result, the amount of incident light can be improved and noise caused by infrared rays (particularly near infrared rays) can be reduced.

  In addition to the first sheet 21 and the second sheet 31, the lens sheet may be provided so as to overlap a third sheet. Furthermore, you may add so that a 4th sheet | seat may be piled up. The structure of the third sheet and the fourth sheet is the same as that of the first sheet, but the direction in which the light transmission part of the third sheet extends is relative to the direction in which the light transmission part 24 of the first sheet 21 extends. It is preferably arranged so as to be shifted by 45 degrees in plan view. Further, when the fourth sheet is further provided, the direction in which the light transmission part of the fourth sheet extends is arranged to be shifted by 90 degrees in plan view with respect to the direction in which the light transmission part of the third sheet extends. It is preferred that

The imaging device 1 including the imaging module 10 as described above operates as follows, for example.
Light from the subject travels into the lens sheet 20 of the imaging module 10 and passes through the first sheet 21 and the second sheet 31. Then, the light is condensed in the arrangement direction of the unit convex lens elements 24 by the unit convex lens elements 24 of the first sheet 21, and is condensed in the arrangement direction of the unit convex lens elements 24 by the unit convex lens elements 24 of the second sheet 31. The At that time, the lens aberration is corrected in each of the unit concave lens element 26 of the first sheet 21 and the unit concave lens element 26 of the second sheet 31.
In addition, at least a part of the light traveling in the direction that forms a large angle with respect to the normal direction of the sheet in the light transmitting portion 22 enters the light absorbing portion 23 and is absorbed. The light transmitted through the lens sheet 20 is focused on the light receiving surface of the image sensor 11.

  In this embodiment, the direction in which the unit convex lens element 24 of the first sheet 21 extends and the direction in which the unit convex lens element 24 of the second sheet extends are arranged so as to be orthogonal to each other in plan view. For example, it is optically equivalent to a form in which the microlenses are two-dimensionally arranged in a lattice pattern. On the light receiving surface of the image sensor 11, images formed by the pseudo microlens are formed without overlapping each other.

In this embodiment, each of the plurality of elements of the image sensor 11 is arranged so as to correspond to each of the pseudo microlenses. At the time of photographing, light divided by the corresponding pseudo microlens enters each element, and the intensity of the light is detected by each element. Further, the incident direction of light incident on the element can be detected from the relationship between each element and the transmitted pseudo microlens.
Information on the intensity and direction of incident light detected by each element obtained in this way is calculated by the image processing means 12, and image data in which the focal length and depth of field are changed after shooting can be generated. is there.

FIG. 8 is a diagram for explaining a state of image formation on the light receiving surface of the image sensor 11 in the imaging module 10 of the present embodiment.
In general, in a light field camera, a plurality of elements located in a predetermined region of the image sensor 11 correspond to one microlens of the microlens array. It is important that the image by each microlens is projected only within the corresponding region.
At this time, for example, as shown in FIG. 8B, when the images of the respective microlenses are projected onto an adjacent region or the like and the images overlap, light having different positions and angles on the subject surface is applied to the same element. A phenomenon called incident crosstalk occurs, and the incident direction and intensity of light cannot be decomposed.
In order to solve this problem, in the conventional light field camera, it is necessary to provide an imaging lens closer to the subject side than the microlens array.

  On the other hand, according to the present embodiment, since the light absorbing portion 23 is provided, the light that travels outside the region is absorbed here, and crosstalk occurs as shown in FIG. The light condensed by the unit convex lens element 24 can be made incident on the element in the corresponding region of the image sensor 11 without being caused to occur. Thereby, the element can output the intensity of incident light and the information on the incident direction with high accuracy.

Therefore, according to this embodiment, it is possible to reduce the thickness and weight of the imaging module without requiring another lens system such as an imaging lens. For example, it can be suppressed to about several tens of μm to several hundreds of μm. Thereby, the external appearance of an imaging device can also be improved.
Further, from the viewpoint of manufacturing, an imaging lens is not necessary, and thus manufacturing costs can be suppressed.

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Case 10 Imaging module 11 Image sensor 12 Image processing device 20 Lens sheet 21 First sheet 22 Light transmission part 23 Light absorption part 24 Unit convex lens element 25 Base part 26 Unit concave lens element 31 Second sheet

Claims (5)

A lens sheet disposed on the light receiving surface side of the image sensor,
A light transmissive portion having a predetermined cross section, extending in one direction along the sheet surface, and arranged in a direction different from the extending direction at a predetermined interval;
A light absorbing portion that is formed in an interval between the light transmitting portions adjacent to each other and absorbs light;
A convex unit convex lens element provided in the light transmitting portion;
A lens sheet comprising: a sheet comprising: a concave unit concave lens element provided on the opposite side across the light transmission part. At least two of the sheets are laminated;
The lens sheet according to claim 1, wherein the two sheets intersect in a plan view in a direction in which the light transmission portion extends. The lens sheet according to claim 1 or 2,
An image pickup module comprising: an image sensor arranged on one side of the lens sheet and arranged with a plurality of photoelectric conversion elements.   The imaging module according to claim 3, wherein the lens sheet is disposed so that the unit convex lens element is disposed on a side opposite to the side on which the image sensor is disposed.   An imaging apparatus in which the imaging module according to claim 3 or 4 is disposed inside a casing.

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