JP2018139394A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high definition imaging device with high wavelength separation accuracy.SOLUTION: An imaging device 1 includes: an optical system 10 including a lens; a filter array 20 having a plurality of filter areas 22 arranged in an array each having different optical characteristics, in which each of the filter areas 22 wavelength selectively transmits light transmitted through the optical system 10; an image sensor 30 having a plurality of sub pixels 32 which are dispose in an array corresponding to each of the plurality of filter areas 22; and a micro-lens array 40 disposed between the filter array 20 and the image sensor 30 for allowing beams of light transmitted through each of the plurality of filter areas 22 to enter the sub-pixels 32. The filter array 20 is a multi-layered thin film interference filter.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus.

  Conventionally, a solid-state imaging device including an on-chip color filter is known (see, for example, Patent Document 1).

JP 2013-8777 A

  The on-chip color filter of the conventional solid-state imaging device is formed using a resin material in which a color pigment is dispersed. A color filter formed using a resin material in which a color pigment is dispersed has a problem that a transmission band is wide and wavelength separation accuracy is low.

  On the other hand, it is conceivable to use a bandpass filter array in which bandpass filters with high wavelength separation accuracy are formed in an array instead of a color filter. However, it is difficult in the process to form the bandpass filter array directly on the image sensor like an on-chip color filter. For this reason, since a gap is generated between the bandpass filter array and the image sensor, there is a problem that light that has passed through one filter region is incident on another pixel without being condensed on one pixel.

  Therefore, an object of the present invention is to provide a high-definition imaging apparatus with high wavelength separation accuracy.

  In order to achieve the above object, an imaging apparatus according to one embodiment of the present invention includes an optical system including a lens and a plurality of filter regions having different optical characteristics arranged in an array, and the light that has passed through the optical system is A filter array that transmits light selectively for each filter region, an image sensor having a plurality of pixels arranged in an array corresponding to each of the plurality of filter regions, and between the filter array and the image sensor And an optical element in the form of an array that allows light that has passed through each of the plurality of filter regions to enter the corresponding pixel, and the filter array is a multilayer thin film interference filter.

  According to the present invention, it is possible to provide a high-definition imaging apparatus with high wavelength separation accuracy.

It is sectional drawing which shows the structure of the imaging device which concerns on embodiment. It is a perspective view which shows the structure of the filter array of the imaging device which concerns on embodiment. It is a top view which shows the unit area | region of the filter array which concerns on embodiment. It is a figure which shows the transmission characteristic of the multiband pass filter with which the filter array which concerns on embodiment is equipped, and the transmission characteristic for every filter area | region. It is a figure which shows the condensing efficiency by the imaging device which concerns on embodiment and a modification. It is sectional drawing which shows the structure of the imaging device which concerns on the modification 1 of embodiment. It is sectional drawing which shows the structure of the imaging device which concerns on the modification 2 of embodiment.

  Hereinafter, an imaging apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. Each of the embodiments described below shows a specific example of the present invention. Therefore, numerical values, shapes, materials, components, arrangement and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as optional constituent elements.

  Each figure is a mimetic diagram and is not necessarily illustrated strictly. Therefore, for example, the scales and the like do not necessarily match in each drawing. Moreover, in each figure, the same code | symbol is attached | subjected about the substantially same structure, The overlapping description is abbreviate | omitted or simplified.

(Embodiment)
[Constitution]
First, the configuration of the imaging device according to the present embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view illustrating a configuration of an imaging apparatus 1 according to the present embodiment.

  As shown in FIG. 1, the imaging device 1 includes an optical system 10, a filter array 20, an image sensor 30, a microlens array 40, and a housing 50. The filter array 20, the image sensor 30, and the microlens array 40 are housed in a housing 50, and the optical system 10 is disposed so as to close an opening provided in the housing 50. The optical system 10, the filter array 20, the microlens array 40, and the image sensor 30 are arranged in this order. The light that has passed through the optical system 10 passes through the filter array 20 and the microlens array 40 in this order, and enters the image sensor 30. The image sensor 30 generates an electrical signal (pixel signal) corresponding to the intensity of incident light and outputs it to the outside.

  Below, each structural member which comprises the imaging device 1 is demonstrated in detail.

[Optical system]
The optical system 10 includes a lens. Although one lens is schematically shown in FIG. 1, the optical system 10 may include a plurality of lenses. For example, the optical system 10 condenses incident light from the outside (hereinafter simply referred to as incident light) stepwise by a plurality of lenses, thereby converting the incident light into parallel light and exiting it toward the filter array 20. To do.

[Filter array]
FIG. 2 is a perspective view showing the configuration of the filter array 20 according to the present embodiment. As shown in FIG. 2, the filter array 20 includes a first band pass filter (BPF) 24 and a second band pass filter (BPF) 25. Although not shown in FIG. 2, the filter array 20 includes a substrate 21 as shown in FIG. A first BPF 24 and a second BPF 25 are sequentially stacked on the substrate 21. The board | substrate 21 is formed using the translucent base material which has translucency. As a translucent base material, they are transparent resin substrates, such as a polyethylene terephthalate (PET) film, or a transparent glass substrate, for example.

  In the filter array 20, a plurality of filter regions 22 having different optical characteristics are arranged in an array, and light that has passed through the optical system 10 is selectively transmitted for each filter region 22. In the present embodiment, the filter array 20 is a multilayer thin film interference filter. The plurality of filter regions 22 are divided by the difference between overlap and non-overlap between the first BPF 24 and the second BPF 25.

  Each of the first BPF 24 and the second BPF 25 is a multiband pass filter having a light transmission band in two wavelength regions that do not overlap each other. The transmission characteristics of the first BPF 24 and the second BPF 25 will be described later with reference to FIG.

  Each of the first BPF 24 and the second BPF 25 is a thin film interference filter having a multilayer structure in which three or more thin films are stacked. The first BPF 24 and the second BPF 25 having a light transmission band in a desired wavelength band can be realized by appropriately designing the film thickness, refractive index, and number of stacked layers of the thin film constituting the multilayer structure.

The thin film is, for example, an inorganic film using a dielectric material. Specifically, the thin film is a silicon oxide (SiO _x ) film, a titanium oxide (TiO _x ) film, or the like. Each thin film is formed on the substrate 21 by vapor deposition, sputtering, or the like. The film thicknesses of the first BPF 24 and the second BPF 25 are, for example, 1 μm to 5 μm, but are not limited thereto.

  As shown in FIG. 2, the first BPF 24 and the second BPF 25 are each formed in a line-and-space shape (stripe shape) in plan view. The lines and spaces of the first BPF 24 have the same width, but may be different. Moreover, although each width | variety of a some line and each width | variety of a some space are the same width | variety, they may differ. The same applies to the second BPF 25.

  In the present embodiment, the first BPF 24 and the second BPF 25 are provided so that the respective lines intersect. Specifically, the first BPF 24 and the second BPF 25 are orthogonal to each other. That is, each line of the first BPF 24 and the second BPF 25 overlaps in plan view. An optical characteristic (specifically, a light transmission band) differs between a region where the first BPF 24 and the second BPF 25 overlap and a region where the first BPF 24 does not overlap. Thereby, a plurality of filter regions 22 having different optical characteristics are formed in the filter array 20 in plan view.

  FIG. 3 is a plan view showing the unit region 23 of the filter array 20 according to the present embodiment. In the filter array 20, a plurality of unit regions 23 are arranged in an array. Each of the plurality of unit areas 23 includes a plurality of filter areas 22. Specifically, the plurality of filter regions 22 include a first filter region 22a, a second filter region 22b, a third filter region 22c, and a total transmission region 22d. In the present embodiment, the unit region 23 is composed of four filter regions 22 arranged in 2 rows and 2 columns.

  The first filter region 22a is a region where only the first BPF 24 is provided among the first BPF 24 and the second BPF 25. The second filter region 22b is a region where only the second BPF 25 is provided among the first BPF 24 and the second BPF 25. The third filter region 22c is a region where both the first BPF 24 and the second BPF 25 are overlapped. The total transmission region 22d is a region where neither the first BPF 24 nor the second BPF 25 is provided. The light passing through the total transmission region 22d is the incident light itself incident on the filter array 20.

  In the present embodiment, the first filter region 22a, the second filter region 22b, the third filter region 22c, and the total transmission region 22d have the same shape and size. Specifically, each of the first filter region 22a, the second filter region 22b, the third filter region 22c, and the total transmission region 22d is formed in a substantially square shape having the same area in plan view. As a result, the amount of light incident on each filter region 22 can be made substantially the same. As shown in FIG. 1, each of the first filter region 22a, the second filter region 22b, and the third filter region 22c includes a first sub-pixel 32a, a second sub-pixel 32b, and a third sub-pixel 32c of the image sensor 30, respectively. One-to-one correspondence.

  In FIG. 1, for the sake of simplicity, the stacking relationship between the first BPF 24 and the second BPF 25 is not shown, and the first filter region 22a, the second filter region 22b, and the third filter region 22c are arranged in one direction. The example arrange | positioned by is shown typically. Further, the total transmission region 22d is not shown. Actually, as shown in FIG. 2, the first BPF 24 and the second BPF 25 are overlapped (the overlapping portion is the third filter region 22c), and as shown in FIG. 3, the first filter region 22a and It is not adjacent to the second filter region 22b. The arrangement of the filter regions is not limited to the example shown in FIG. 3, and may be arranged in order in one direction as shown in FIG.

  Hereinafter, the optical characteristics of each BPF and each filter region 22 will be described with reference to FIG. FIG. 4 is a diagram showing the transmission characteristics of the multiband pass filter included in the filter array 20 according to the present embodiment and the transmission characteristics for each filter region 22. Specifically, FIGS. 4A to 4C schematically show the transmission characteristics of the first filter region 22a, the second filter region 22b, and the third filter region 22c, respectively. The horizontal axis represents the wavelength, and the vertical axis represents the transmittance.

  Since only the first BPF 24 is provided in the first filter region 22a, the optical characteristics of the first filter region 22a coincide with the optical characteristics of the first BPF 24. Specifically, as shown in FIG. 4A, the first BPF 24 has a first transmission band 61 and a second transmission band 62 that do not overlap each other. A cutoff band 71 is provided between the first transmission band 61 and the second transmission band 62.

  The first transmission band 61 is, for example, a wavelength band having a center wavelength of about 450 nm and a bandwidth of about 50 nm. The first transmission band 61 is a wavelength band for mainly transmitting blue light (B). Here, the center wavelength is a wavelength at the median bandwidth. The bandwidth is the width of the transmission band at a portion where the absolute light transmittance is 50%.

  For example, the second transmission band 62 is a wavelength band having a larger center wavelength than the first transmission band 61. The second transmission band 62 is, for example, a wavelength band having a center wavelength of about 550 nm and a bandwidth of about 50 nm. The second transmission band 62 is a wavelength band for mainly transmitting green light (G).

  The cut-off band 71 has a light transmittance of 10% or less. The first BPF 24 has no light transmission band other than the first transmission band 61 and the second transmission band 62. Specifically, in the first BPF 24, the light transmittance in other wavelength bands excluding the first transmission band 61 and the second transmission band 62 is 10% or less.

  In the present embodiment, the first BPF 24 has a first transmission band 61 that transmits blue light and a second transmission band 62 that transmits green light. Therefore, the first BPF 24 transmits light containing cyan and blue components. Let Therefore, the first filter region 22a provided with only the first BPF 24 is a region that transmits cyan light (C) and does not substantially transmit light of other color components (wavelength components).

  Since only the second BPF 25 is provided in the second filter region 22b, the optical characteristics of the second filter region 22b and the optical characteristics of the second BPF 25 match. Specifically, as shown in FIG. 4B, the second BPF 25 has a third transmission band 63 and a fourth transmission band 64 that do not overlap each other. A cutoff band 72 is provided between the third transmission band 63 and the fourth transmission band 64.

  The third transmission band 63 is, for example, a wavelength band having a center wavelength of about 550 nm and a bandwidth of about 50 nm. The third transmission band 63 is a wavelength band for mainly transmitting green light.

  For example, the fourth transmission band 64 is a wavelength band having a larger center wavelength than the third transmission band 63. For example, the fourth transmission band 64 is a wavelength band having a center wavelength of about 650 nm and a bandwidth of about 50 nm. The fourth transmission band 64 is a wavelength band for mainly transmitting red light.

  The cutoff band 72 has a light transmittance of 10% or less. The second BPF 25 has no light transmission band other than the third transmission band 63 and the fourth transmission band 64. Specifically, in the second BPF 25, the light transmittance in other wavelength bands excluding the third transmission band 63 and the fourth transmission band 64 is 10% or less.

  In the present embodiment, since the second BPF 25 has the third transmission band 63 that transmits green light and the fourth transmission band 64 that transmits red light, the second BPF 25 transmits light (yellow light) including a green component and a red component. Let Accordingly, the second filter region 22b provided with only the second BPF 25 is a region that transmits yellow light (Y) and does not substantially transmit light of other color components (wavelength components).

  As shown in FIGS. 4A and 4B, the second transmission band 62 of the first BPF 24 and the third transmission band 63 of the second BPF 25 overlap. Specifically, the second transmission band 62 and the third transmission band 63 coincide with each other. Further, the first transmission band 61 and the fourth transmission band 64 do not overlap.

  Note that the second transmission band 62 and the third transmission band 63 do not have to completely coincide with each other. Specifically, the second transmission band 62 and the third transmission band 63 may have different bandwidths, rising and falling wavelengths, average and maximum transmittance values, and the like. For example, the second transmission band 62 may be included in the third transmission band 63, and the third transmission band 63 may be included in the second transmission band 62. For example, most of the second transmission band 62 (for example, 90% or more of the bandwidth) and most of the third transmission band 63 may coincide.

  In the present embodiment, the light transmittance in each of the first transmission band 61 to the fourth transmission band 64 is 90% or more. The light transmittance may be 95% or more. The light transmittance in the transmission band is, for example, the transmittance at the center wavelength of the transmission band. The center wavelength and the bandwidth of each of the first transmission band 61 to the fourth transmission band 64 are not limited to the above example. The bandwidth may be a value determined within a range of 20 nm to 80 nm, for example.

  Since the first BPF 24 and the second BPF 25 are disposed so as to overlap each other in the third filter region 22c, the optical characteristic of the third filter region 22c is an optical characteristic obtained by multiplying the first BPF 24 and the second BPF 25.

  Specifically, as shown in FIG. 4C, the third filter region 22 c has only the second transmission band 62 (third transmission band 63) as the transmission band 65. In the present embodiment, since the second transmission band 62 transmits green components, the third filter region 22c transmits green light (G) and substantially transmits light of other color components (wavelength components). This is a region that is not transparent.

  In the present embodiment, an example in which the second transmission band 62 and the third transmission band 63 overlap (specifically match) is shown, but the present invention is not limited to this. For example, the second BPF 25 may have a first transmission band 61 instead of the third transmission band 63. Alternatively, the first BPF 24 may have a fourth transmission band 64 instead of the second transmission band 62.

[Image sensor]
The image sensor 30 has a plurality of sub-pixels 32 arranged in an array corresponding to each of the plurality of filter regions 22. The image sensor 30 is a CCD image sensor or a CMOS image sensor.

  In the present embodiment, as shown in FIG. 1, the image sensor 30 includes a substrate 31, a plurality of subpixels 32 formed on the substrate 31, and an on-chip microlens 34. The on-chip microlens 34 is disposed on the light incident surface side of the substrate 31. The on-chip microlens 34 is provided with a plurality of lenses corresponding to the plurality of subpixels 32 on a one-to-one basis, and is an example of an optical element for condensing light incident on the image sensor 30 onto the subpixels 32. .

  Each of the plurality of subpixels 32 includes, for example, a photodiode or a phototransistor, and outputs a pixel signal corresponding to the received light intensity by photoelectrically converting the received light. The plurality of subpixels 32 include a first subpixel 32a, a second subpixel 32b, and a third subpixel 32c.

  The light that has passed through the first filter region 22a is incident on the first sub-pixel 32a. Since the first filter region 22a transmits cyan light (C), the first sub-pixel 32a receives the cyan light and performs photoelectric conversion to output a pixel signal corresponding to the received light intensity of the cyan light.

  The light that has passed through the second filter region 22b is incident on the second sub-pixel 32b. Since the second filter region 22b transmits yellow light (Y), the second sub-pixel 32b receives yellow light and performs photoelectric conversion, thereby outputting a pixel signal corresponding to the received light intensity of the yellow light.

  Light that has passed through the third filter region 22c is incident on the third sub-pixel 32c. Since the third filter region 22c transmits green light (G), the third sub-pixel 32c receives the green light and performs photoelectric conversion to output a pixel signal corresponding to the received light intensity of the green light.

  In the present embodiment, like the filter array 20, the four subpixels 32 constitute one unit pixel 33. Specifically, a first sub-pixel 32a corresponding to the first filter region 22a, a second sub-pixel 32b corresponding to the second filter region 22b, a third sub-pixel 32c corresponding to the third filter region 22c, A unit pixel 33 is configured by a fourth sub-pixel (not shown) corresponding to the total transmission region 22d. The unit pixels 33 have a one-to-one correspondence with the unit regions 23 of the filter array 20. Note that the pixel signal generated from the fourth sub-pixel on which the light that has passed through the total transmission region 22d is incident can be used to remove noise components.

[Microlens array (arrayed optical element)]
The microlens array 40 is an example of an array-like optical element that causes light that has passed through each of the plurality of filter regions 22 to enter the corresponding subpixel 32. The microlens array 40 is disposed between the filter array 20 and the image sensor 30.

  In the present embodiment, as shown in FIG. 1, the microlens array 40 includes a first base material 41 and a plurality of first convex lenses 42. The plurality of first convex lenses 42 is the main surface of the first base material 41 and is arranged in an array on the main surface 41a on the image sensor 30 side. The plurality of first convex lenses 42 correspond one-to-one to each of the plurality of filter regions 22 of the filter array 20 and the plurality of sub-pixels 32 of the image sensor 30. For example, the number of the plurality of first convex lenses 42 is the same as the number of the plurality of filter regions 22 and the same as the number of the plurality of sub-pixels 32.

  The shape of the plurality of first convex lenses 42 is, for example, a dome shape such as a hemisphere or a semi-elliptical sphere, but is not limited thereto. For example, when the filter array 20 is viewed from the light incident surface side, the first convex lens 42, the corresponding filter region 22, and the corresponding sub-pixel 32 are arranged so as to overlap each other.

  The microlens array 40 is stacked on the main surface of the filter array 20 on the image sensor 30 side. The microlens array 40 is bonded to the filter array 20 via, for example, an adhesive sheet.

  The microlens array 40 is integrally formed using, for example, a translucent resin material such as acrylic or polycarbonate, or a translucent glass material. The plurality of first convex lenses 42 are in contact with air (air layer), and condense light emitted from the first convex lens 42 on the corresponding sub-pixels 32 due to a difference in refractive index with air.

  In the present embodiment, since the microlens array 40 is provided between the filter array 20 and the image sensor 30, the light that has passed through each filter region 22 of the filter array 20 is applied to the corresponding subpixel 32. Condensation efficiency can be increased. In order to confirm the effect of improving the light collection efficiency, the inventors performed a simulation. The simulation result will be described later with reference to FIG.

[Case]
The housing 50 supports the optical system 10, the filter array 20, the image sensor 30, and the microlens array 40. The housing 50 is formed using, for example, a light-blocking resin material, and can prevent external light (noise component) from entering the image sensor 30.

  The housing 50 has, for example, a bottomed cylindrical shape such as a cylinder or a square tube. The optical system 10 is provided in the opening of the housing 50, and the image sensor 30 is disposed inside the bottom of the housing 50.

  The housing 50 includes a support portion 51 that supports the filter array 20 and the microlens array 40. The support unit 51 supports the microlens array 40 away from the image sensor 30. Specifically, a gap, that is, an air layer is provided between the microlens array 40 and the on-chip microlens 34 of the image sensor 30. The support portion 51 is a groove (concave portion) or protrusion provided in the housing 50, and supports the filter array 20 by engaging with the protrusion or groove provided in the filter array 20. Note that the support unit 51 may support the microlens array 40 by engaging with protrusions or grooves provided in the microlens array 40.

  The filter array 20 and the image sensor 30 are arranged, for example, 0.5 mm apart. For this reason, the microlens array 40 and the image sensor 30 are arranged, for example, with a distance greater than 0 mm and less than 0.5 mm.

[Signal processing]
Subsequently, a signal processing method using the filter array 20 according to the present embodiment will be described. The signal processing method is performed by, for example, a signal processing circuit (not shown) included in the imaging device 1.

  The signal processing circuit acquires a pixel signal from each sub pixel 32 for each unit pixel 33. Specifically, the signal processing circuit acquires a first signal S1 that is a light reception signal of light (cyan light) transmitted through the first filter region 22a from the first sub-pixel 32a. The signal processing circuit acquires a second signal S2 that is a light reception signal of light (yellow light) transmitted through the second filter region 22b from the second sub-pixel 32b. The signal processing circuit acquires a third signal S3, which is a light reception signal of light (green light) transmitted through the third filter region 22c, from the third sub-pixel 32c. The first signal S1, the second signal S2, and the third signal S3 are electrical signals corresponding to the intensities of cyan light (C), yellow light (Y), and green light (G), respectively.

  The signal processing circuit generates a signal corresponding to the light in the first transmission band 61 by subtracting the third signal S3 from the first signal S1. Specifically, since the green component corresponding to the second transmission band 62 and the third transmission band 63 is canceled and only the blue component corresponding to the first transmission band 61 remains, it depends on the intensity of the blue light (B). Color signals can be generated.

  The signal processing circuit generates a signal corresponding to the light in the fourth transmission band 64 by subtracting the third signal S3 from the second signal S2. Specifically, since the green component corresponding to the second transmission band 62 and the third transmission band 63 is canceled and only the red component corresponding to the fourth transmission band 64 remains, it depends on the intensity of the red light (R). Color signals can be generated.

  The signal processing circuit can use the third signal S3 as it is as a color signal corresponding to the intensity of the green light (G).

  As described above, the signal processing circuit can generate RGB color signals. As described above, by using the filter array 20 according to the present embodiment, signals of three wavelength components can be generated from the two filters (the first BPF 24 and the second BPF 25). That is, many wavelength components can be extracted with a small number of filters.

[Effects, etc.]
As described above, the imaging apparatus 1 according to the present embodiment includes the optical system 10 including a lens and a plurality of filter regions 22 having different optical characteristics arranged in an array, and filters light that has passed through the optical system 10. Each of the regions 22 includes a filter array 20 that selectively transmits light, and an image sensor 30 that includes a plurality of sub-pixels 32 that correspond to each of the plurality of filter regions 22 and are arranged in an array. The imaging device 1 is further arranged between the filter array 20 and the image sensor 30, and is a micro optical element that is an array-like optical element that causes light that has passed through each of the plurality of filter regions 22 to enter the corresponding sub-pixel 32. A lens array 40 is provided. The filter array 20 is a multilayer thin film interference filter.

  Thereby, since the filter array 20 is a multilayer thin film interference filter, higher wavelength separation can be realized as compared with a pigment-based color filter. Furthermore, since the light that has passed through each filter region 22 of the filter array 20 is condensed on the corresponding sub-pixel 32 by the microlens array 40, the light collection efficiency can be increased.

  Here, a simulation result performed for confirming improvement of the light collection efficiency will be described with reference to FIG. FIG. 5 is a diagram showing the light collection efficiency by the imaging apparatus 1 according to the present embodiment. Note that FIG. 5 also shows the light collection efficiency of the imaging apparatus according to a modified example described later.

  The imaging device according to the comparative example illustrated in FIG. 5 has a configuration in which the microlens array 40 is removed from the imaging device 1 according to the present embodiment. In addition, the light collection efficiency indicates a result of simulation for three types of light according to the angle of light incident on the filter array 20. Specifically, the three types of light include light along the optical axis of the optical system 10 (incident angle 0 °), light having an incident angle of approximately 10.6 °, and incident angle of approximately 17.35 °. It is light that becomes.

  The light collection efficiency is a ratio of light incident on the corresponding sub-pixel 32 of the image sensor 30 out of the light collected on the filter region 22 of the filter array 20. That is, when all of the light incident on the filter region 22 at a predetermined incident angle is incident on the corresponding sub-pixel 32, the light collection efficiency is 100%.

  As shown in FIG. 5, in the comparative example, the light collection efficiency of the light traveling on the optical axis was about 6.6%. The light collection efficiency of the two obliquely incident lights was also about 5.7%, which was about 1.3%. That is, when the microlens array 40 is not provided, it can be seen that most of the light collected by one filter region 22 of the filter array 20 does not enter the corresponding subpixel 32.

  On the other hand, in this Embodiment, the condensing efficiency of the light which advanced on the optical axis was about 100%. The light collection efficiency of the two obliquely incident lights was about 95.8% and about 81.3%. Thus, it can be seen that the provision of the microlens array 40 dramatically improves the light collection efficiency.

  From the above, according to the present embodiment, it is possible to realize a high-definition imaging apparatus 1 with high wavelength separation accuracy.

  For example, the filter array 20 includes a first BPF 24 having a first transmission band 61 and a second transmission band 62 that do not overlap with each other, and a second BPF 25 having a third transmission band 63 and a fourth transmission band 64 that do not overlap with each other. Is provided. The first transmission band 61 and the fourth transmission band 64 do not overlap, and the second transmission band 62 and the third transmission band 63 overlap. The plurality of filter regions 22 include a first filter region 22a in which only the first BPF 24 of the first BPF 24 and the second BPF 25 is provided, a second filter region 22b in which only the second BPF 25 of the first BPF 24 and the second BPF 25 is provided, And a third filter region 22c in which both the first BPF 24 and the second BPF 25 are overlaid.

  Thus, each of the first BPF 24 and the second BPF 25 is a multiband pass filter having two transmission bands that do not overlap each other. The multiband pass filter can sufficiently attenuate light in a wavelength band other than the transmission band. Therefore, the noise component contained in the light that has passed through each filter region in which at least one of the first BPF 24 and the second BPF 25 is provided can be sufficiently reduced. That is, the SN ratio can be increased, and the accuracy of wavelength separation (color separation) can be increased.

  Further, according to the imaging apparatus 1 according to the present embodiment, color signals corresponding to three wavelength bands can be generated by two multiband pass filters. That is, it is possible to generate color signals in a wavelength band larger than the number of filters with a small number of filters. By reducing the number of filters, the filter array 20 can be reduced in weight, the manufacturing process can be simplified, and the cost can be reduced.

  For example, the number of alignment (positioning) steps in the manufacturing process can be reduced. For example, when manufacturing a filter array including three bandpass filters for RGB, at least two alignments are required. On the other hand, in the present embodiment, the first BPF 24 and the second BPF 25 need only be aligned once.

  Further, for example, the microlens array 40 includes a plurality of first convex lenses 42 arranged in an array on the main surface 41a on the image sensor 30 side, and is laminated on the main surface on the image sensor 30 side of the filter array 20. Yes.

  Accordingly, as described with reference to FIG. 5, the light condensed on the filter region 22 can be condensed on the corresponding sub-pixel 32 with high light collection efficiency. For this reason, the high-definition imaging device 1 with high wavelength separation accuracy can be realized.

  In addition, for example, the plurality of filter regions 22, the plurality of sub-pixels 32, and the plurality of first convex lenses 42 correspond to one by one.

  Thereby, since the filter region 22, the sub pixel 32, and the 1st convex lens 42 respond | correspond one by one, each design and arrangement | positioning become easy. For this reason, the high-definition imaging device 1 can be easily realized.

(Modification)
Subsequently, modified examples 1 and 2 of the embodiment will be described.

  In the modification shown below, the configuration of the microlens array is different from that of the embodiment. In the following description, differences from the embodiment will be mainly described, and description of common points will be omitted or simplified.

[Modification 1]
FIG. 6 is a cross-sectional view showing the configuration of the imaging apparatus 101 according to this modification.

  As illustrated in FIG. 6, the imaging apparatus 101 is different from the imaging apparatus 1 according to the embodiment in that the imaging apparatus 101 includes a microlens array 140 and a casing 150 instead of the microlens array 40 and the casing 50. To do.

  The microlens array 140 has a plurality of second convex lenses 142. The plurality of second convex lenses 142 are arranged in an array on the main surface 41b on the filter array 20 side. The plurality of second convex lenses 142 correspond one-to-one to each of the plurality of filter regions 22 of the filter array 20 and the plurality of sub-pixels 32 of the image sensor 30. For example, the number of the plurality of second convex lenses 142 is the same as the number of the plurality of filter regions 22 and the number of the plurality of sub-pixels 32.

  The shape of the second convex lens 142 is, for example, a dome shape such as a hemisphere or a semi-elliptical sphere, but is not limited thereto. For example, when the filter array 20 is viewed from the light incident surface side, the second convex lens 142, the corresponding filter region 22, and the corresponding sub-pixel 32 are arranged so as to overlap each other.

  In this modification, the microlens array 140 is supported by the housing 150. The housing 150 supports the microlens array 140 apart from the filter array 20. Specifically, as illustrated in FIG. 1, the housing 150 includes a support portion 151 that supports the filter array 20 and a support portion 152 that supports the microlens array 140.

  The support portion 151 is a groove (concave portion) or protrusion provided in the housing 150, and supports the filter array 20 by engaging with the protrusion or groove provided in the filter array 20. The support portion 152 is a groove (concave portion) or protrusion provided in the housing 150, and supports the microlens array 140 by engaging with the protrusion or groove provided in the microlens array 140.

  The distance between the microlens array 140 and the filter array 20 is, for example, a distance greater than 0 mm and less than 0.5 mm. The second convex lens 142 of the microlens array 140 is not in contact with the filter array 20 and an air layer is interposed therebetween. For example, the microlens array 140 is disposed at a position closer to the filter array 20 than the image sensor 30.

  As described above, the imaging apparatus 101 according to the present modification includes, for example, the housing 150 that supports the optical system 10, the filter array 20, the image sensor 30, and the microlens array 140. The microlens array 140 has a plurality of second convex lenses 142 arranged in an array on the main surface 41b on the filter array 20 side. The housing 150 supports the microlens array 140 apart from the filter array 20.

  As shown in FIG. 5, in this modification, the light collection efficiency of the light traveling on the optical axis was about 93.7%. In addition, the light collection efficiency of the two obliquely incident lights was about 95.6% and about 75.4%. As described above, also in the imaging apparatus 101 according to this modification, it is possible to achieve the same light collection efficiency as that of the imaging apparatus 1 according to the embodiment.

  Further, for example, the plurality of filter regions 22, the plurality of sub-pixels 32, and the plurality of second convex lenses 142 each correspond to one by one.

  As a result, the filter region 22, the sub-pixel 32, and the second convex lens 142 correspond to each other, so that each design and arrangement is simplified. For this reason, the high-definition imaging device 101 can be easily realized.

[Modification 2]
FIG. 7 is a cross-sectional view showing the configuration of the imaging apparatus 201 according to this modification.

  As illustrated in FIG. 7, the imaging apparatus 201 is different from the imaging apparatus 101 according to the modified example 1 in that a microlens array 240 is provided instead of the microlens array 140.

  The microlens array 240 includes a plurality of first convex lenses 42 and a plurality of second convex lenses 142. That is, the microlens array 240 is provided with convex lenses on both sides of the filter array 20 side and the image sensor 30 side. The first convex lens 42 and the second convex lens 142 are the same as those shown in the embodiment and the first modification, respectively.

  In this modification, the microlens array 240 is supported by the housing 150. The housing 150 supports the microlens array 240 separately from each of the filter array 20 and the image sensor 30. Specifically, as illustrated in FIG. 1, the housing 150 includes a support portion 151 that supports the filter array 20 and a support portion 152 that supports the microlens array 240. The support portion 152 is a groove (concave portion) or protrusion provided in the housing 150, and supports the microlens array 240 by engaging with the protrusion or groove provided in the microlens array 240.

  Note that the distance between the microlens array 240 and the filter array 20 and the distance between the microlens array 240 and the image sensor 30 are each greater than 0 mm and less than 0.5 mm, for example. The first convex lens 42 of the microlens array 240 is not in contact with the image sensor 30 and an air layer is interposed therebetween. Similarly, the second convex lens 142 of the microlens array 240 is not in contact with the image sensor 30 and an air layer is interposed therebetween. For example, the microlens array 240 is disposed at the center between the image sensor 30 and the filter array 20.

  As described above, in the imaging apparatus 201 according to the present modification, for example, the microlens array 240 includes the plurality of first convex lenses 42 arranged in an array on the main surface 41a on the image sensor 30 side, and the filter array 20 side. And a plurality of second convex lenses 142 arranged in an array on the main surface 41b. The housing 150 supports the microlens array 240 separately from each of the filter array 20 and the image sensor 30.

  As shown in FIG. 5, in the present modification, the light collection efficiency of the light traveling on the optical axis was approximately 100%. In addition, the light collection efficiency of the two obliquely incident lights was about 96.6%, which was about 96.6%. As described above, the imaging apparatus 201 according to the present modification can realize light collection efficiency that is even better than that of the imaging apparatus 1 according to the embodiment.

  Further, for example, the plurality of filter regions 22, the plurality of sub-pixels 32, the plurality of first convex lenses 42, and the plurality of second convex lenses 142 respectively correspond to each other.

  Thereby, since the filter region 22, the sub-pixel 32, the first convex lens 42, and the second convex lens 142 correspond to each other, the design and arrangement of each are simplified. For this reason, the high-definition imaging device 1 can be easily realized.

(Other)
As described above, the imaging apparatus according to the present invention has been described based on the above-described embodiment and its modifications. However, the present invention is not limited to the above-described embodiment.

  For example, in the above-described embodiment, an example in which the microlens array and the filter array are supported by the housing has been described, but the present invention is not limited thereto. For example, the microlens array may be supported by a resin material that fills the space between the image sensors. At this time, as the resin material, a material having a refractive index different from that of the convex lens of the microlens array is used. Thereby, the light that has passed through the filter region can be effectively incident on the corresponding sub-pixel by the convex lens of the microlens array.

  In addition, for example, in the above-described embodiment, two multiband pass filters are arranged in an overlapping manner, but the present invention is not limited to this. For example, band pass filters may be formed in a matrix for each filter region. For example, a BPF that transmits only red light, a BPF that transmits only green light, and a BPF that transmits only blue light may be arranged in a Bayer arrangement. Each filter region is provided with only one BPF, and a filter region in which a plurality of BPFs are overlapped may not be provided.

  Further, for example, in the above-described embodiment, the first BPF 24 and the second BPF 25 are stacked on one substrate 21, but the present invention is not limited to this. The first BPF 24 may be stacked on one of the two substrates, and the second BPF 25 may be stacked on the other. A filter array can be formed by bonding a substrate on which the first BPF 24 is laminated and a substrate on which the second BPF 25 is laminated.

  Further, for example, in the above-described embodiment, an example in which the first BPF 24 and the second BPF 25 have two transmission bands has been described, but three or more transmission bands may be included.

  For example, in the above-described embodiment, an example in which the transmission band of each BPF has ideal transmission characteristics (rectangular shape with sharp rise and fall) has been described, but the present invention is not limited thereto. For example, the transmission band of each BPF may have a Gaussian function shape.

  For example, the array-shaped optical element is not limited to a microlens array in which convex lenses are formed in a dot shape. For example, when each filter region and each sub-pixel are formed in a line shape, the arrayed optical element may be an element in which a convex lens is formed in a line shape. For example, the microlens array may have a plurality of concave lenses.

  Further, for example, the number of filter regions of the arrayed optical element and the number of pixels of the image sensor do not necessarily match. For example, one filter area may correspond to four pixels of the image sensor, or one filter area may correspond to nine pixels of the image sensor.

  In addition, the embodiment can be realized by arbitrarily combining the components and functions in each embodiment without departing from the scope of the present invention, or a form obtained by subjecting each embodiment to various modifications conceived by those skilled in the art. Forms are also included in the present invention.

1, 101, 201 Imaging device 10 Optical system 20 Filter array 22 Filter region 22a First filter region 22b Second filter region 22c Third filter region 24 First BPF (first bandpass filter)
25 2nd BPF (2nd bandpass filter)
30 Image sensor 32 Sub-pixel 40, 140, 240 Micro lens array (optical element)
41a Main surface (first main surface)
41b Main surface (second main surface)
42 First convex lenses 50 and 150 Case 61 First transmission band 62 Second transmission band 63 Third transmission band 64 Fourth transmission band 142 Second convex lens

Claims (8)

An optical system including a lens;
A plurality of filter regions having different optical characteristics are arranged in an array, and a filter array that selectively transmits light that has passed through the optical system for each filter region;
An image sensor having a plurality of pixels arranged in an array corresponding to each of the plurality of filter regions;
An array-shaped optical element that is disposed between the filter array and the image sensor and causes light that has passed through each of the plurality of filter regions to enter the corresponding pixel;
The filter array is a multilayer thin film interference filter. The filter array is
A first bandpass filter having a first transmission band and a second transmission band that do not overlap each other;
A second bandpass filter having a third transmission band and a fourth transmission band that do not overlap each other,
The first transmission band and the fourth transmission band do not overlap,
The second transmission band and the third transmission band overlap,
The plurality of filter regions include
A first filter region in which only the first bandpass filter is provided among the first bandpass filter and the second bandpass filter;
A second filter region in which only the second bandpass filter is provided among the first bandpass filter and the second bandpass filter;
The imaging device according to claim 1, further comprising: a third filter region in which both the first bandpass filter and the second bandpass filter are overlapped. The imaging apparatus according to claim 1, wherein the arrayed optical element is a microlens array. The array-shaped optical element has a plurality of first convex lenses arranged in an array on the first main surface on the image sensor side, and is stacked on the main surface on the image sensor side of the filter array. Item 4. The imaging device according to Item 3. further,
A housing that supports the optical system, the filter array, the image sensor, and the arrayed optical elements;
The array-shaped optical element has a plurality of second convex lenses arranged in an array on the second main surface on the filter array side,
The imaging device according to claim 3, wherein the casing supports the optical element in the form of an array apart from the filter array. The imaging apparatus according to claim 5, wherein the plurality of filter regions and the plurality of second convex lenses respectively correspond to each other. The array-shaped optical element further includes a plurality of first convex lenses arranged in an array on the first main surface on the image sensor side,
The imaging apparatus according to claim 5, wherein the housing supports the optical element in the array shape apart from each of the filter array and the image sensor. The imaging device according to claim 4 or 7, wherein each of the plurality of filter regions and the plurality of first convex lenses correspond to each other.

Images