JP2016219500A - Imaging device package and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve contrast by preventing displacement between an imaging device and an optical filter in which areas of different optical characteristics are cyclically arranged so as to correspond to pixels, and reducing cross-talk.SOLUTION: An imaging device package comprises: an optical filter 10 in which areas of different optical characteristics are disposed in correspondence with a plurality of pixels; and an imaging device 20 having a pixel array composed of a plurality of light receiving elements 24, and receiving light passed through the optical filter 10. The imaging device 20 has on the surface facing the optical filter 10 a micro-lens array in which a micro-lens 22 for condensing light for each pixel is disposed in correspondence with the pixel. The optical filter 10 has in at least part of a face facing the micro-lens 22 an alignment structure 14 in which a recessed part is formed so as to allow accommodation of the micro-lens 22. By accommodating the micro-lens 22 in the recessed part of the alignment structure 14, the optical filter 10 and imaging device 20 are positioned relative to each other.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an imaging element package and an imaging apparatus.

  There is known an imaging apparatus that generates image information obtained by extracting only a desired polarization component, image information obtained by extracting only a desired wavelength band, and the like from an image signal obtained by imaging a predetermined imaging area. Such an imaging apparatus, for example, two-dimensionally receives a large number of light receiving elements from an optical filter such as a polarizing filter or a spectral filter by using only a desired polarization component or wavelength component (desired optical component) from the light from the imaging region. Light is received by the arranged light receiving element array. Thereby, the image information of the imaging area which extracted the desired optical component according to the light reception amount received by each light receiving element can be obtained.

  For example, as an optical filter, a polarizer array that is divided into two or more polarizer regions each having a different transmission axis is used, and a light receiving element array that independently receives light transmitted through each region of the polarizer array is provided. The imaging apparatus can obtain image information obtained by extracting two or more different polarization components from each other in one imaging operation.

  An optical component extracted image generated from a plurality of different optical components is preferably used for, for example, an object identification process for identifying an object in an imaging region. By using such an optical component extraction image, it becomes possible to identify an object with higher accuracy than when performing object identification processing with image information (monochrome image information) consisting only of luminance information. It is expected to be used for an in-vehicle camera, an imaging device for an object identification device used for robot control, and the like.

  In such an imaging apparatus (polarization camera), it is necessary to use a polarizer array (optical filter) in which each polarizer region is periodically arranged so as to correspond to an imaging pixel on a one-to-one basis. In order to appropriately obtain image information on a plurality of polarization components using a polarizer array (optical filter), each polarizer region of the polarizer array and one or several light receiving elements on the light receiving element array are used. It is necessary to align the image pickup pixels to be one-to-one. Therefore, sub-pixel level positional accuracy is required for alignment between the polarizer array and the light receiving element array.

As a technique for arranging optical components constituting the apparatus with high positional accuracy, for example, a technique for decentering an optical fiber and a collimator lens of an optical fiber collimator by a desired eccentric amount has been proposed (see Patent Document 1).
In Patent Document 1, the optical fiber and the collimator lens are accommodated in each positioning groove of the substrate so as to be in contact with the inner surface of the groove, so that no complicated alignment work is required. It is described that an optical fiber collimator array with a constant amount of eccentricity can be obtained.

The imaging element is provided with a microlens for collecting light. In an image pickup apparatus in which an optical filter and an image pickup element are combined, there may be a positional shift between the optical filter and the microlens during bonding. Specifically, when an optical filter is bonded onto an imaging element having a microlens on the surface, the filter region may be shifted and bonded to the pixel.
In the imaging device, the technique described in Patent Document 1 is required because a structure in which an optical filter without unevenness is mounted on a microlens array having a convex surface, and high-precision positioning with respect to individual pixels is required. Thus, it is difficult to apply positioning using external parts.

  When the region of the optical filter is bonded to the pixel while being shifted, crosstalk occurs in which a part of light is incident on another adjacent pixel. As a result, light of different polarization components is mixed in one pixel, so that accurate polarization information cannot be acquired, and the performance of the imaging device (polarization camera) is degraded.

  Therefore, the present invention suppresses misalignment between an optical filter in which regions having different optical characteristics are periodically arranged so as to correspond to pixels and an image sensor, reduces crosstalk, and realizes an improvement in contrast. An object is to provide an element package.

  In order to achieve such an object, an image pickup device package according to the present invention includes an optical filter in which regions having different optical characteristics are arranged corresponding to a plurality of pixels, and a pixel array including a plurality of light receiving elements, An image sensor that receives light that has passed through the optical filter, and the image sensor has a microlens that collects light for each pixel on a surface facing the optical filter, corresponding to the pixel. The optical filter has an alignment structure in which a concave portion capable of accommodating the microlens is formed in at least a part of a surface facing the microlens, and the concave portion of the alignment structure By accommodating the microlens, the optical filter and the image sensor are positioned relative to each other. Over di.

  According to the present invention, it is possible to suppress misalignment between an optical filter in which regions having different optical characteristics are periodically arranged so as to correspond to pixels and an image sensor, to reduce crosstalk, and to improve contrast. An image pickup device package can be provided.

It is explanatory drawing of the optical filter which has a polarizer of a wire grid structure. It is a schematic diagram which shows an example of the structure of the image pick-up element package which comprises an imaging device. It is a schematic diagram explaining adhesion | attachment with an optical filter and an image pick-up element. It is a graph which shows the relationship between the position shift of an optical filter and an image pick-up element, and polarization contrast. It is a top view of a polarizer of an optical filter which constitutes an image sensor package of this embodiment, a sectional view, and a mimetic diagram showing position shift correction of an image sensor package. 2A and 2B are a schematic diagram and a partially enlarged view of a configuration showing an example of an image sensor package of the present embodiment. FIG. 2 is a perspective view schematically showing an example of an optical filter constituting the image sensor package of the present embodiment, and a partially enlarged view of the image sensor package. It is the elements on larger scale which show an example of the image sensor package of this embodiment. 2A and 2B are a schematic diagram and a partially enlarged view of a configuration showing an example of an image sensor package of the present embodiment. It is a schematic diagram which shows an example of a structure of the imaging device of this embodiment.

  Hereinafter, an imaging device package and an imaging apparatus according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art, and any aspect is possible. As long as the functions and effects of the present invention are exhibited, the scope of the present invention is included.

[Imaging device]
The imaging device of the present invention includes an imaging element package of the present invention, an imaging lens, and a signal processing unit which will be described later.

FIG. 10 is an explanatory diagram illustrating a schematic configuration of the imaging apparatus according to the present embodiment.
The imaging apparatus 100 includes an imaging lens 40 as a condensing unit, an optical filter 10, an imaging device substrate (sensor substrate) 30 on which an imaging device (image sensor) 20 having a pixel array is mounted, a signal processing unit 50, and the like. Have

  The image sensor substrate 30 functions as a substrate for outputting an output signal of the image sensor 20 to an external circuit board. The image sensor 20 and the image sensor substrate 30 are electrically connected.

  The signal processing means 50 includes an A / D converter that converts an analog electrical signal (the amount of light received by each light receiving element on the image sensor 20) output from the image sensor substrate 30 into a digital electrical signal (pixel signal); A signal processing unit that performs image processing on the digital electrical signal output from the A / D conversion unit to generate and output image data (image information) for each polarization component.

  In the present embodiment, components on the rear side of the imaging lens 40 are packaged. However, there are limitations on the method of assembling the imaging lens 40, the optical filter 10, the imaging element 20, the imaging element substrate 30, and the like that constitute the imaging apparatus 100. Instead, they may be individually assembled to the camera casing, or part or all of them may be packaged.

The optical filter 10 has an alignment structure in a region where a structure (optical function structure) for imparting a desired optical function is selectively formed and a surface facing the light receiving surface of the image sensor 20.
Although it does not specifically limit as an optical filter, For example, a polarizing filter, a color filter, an infrared filter etc. are mentioned.

Hereinafter, a polarization camera including a polarization filter (polarization separation element) as an optical filter will be described as an embodiment.
A polarization camera can acquire information that cannot be acquired in a color image or a black and white image by mounting a polarization filter on the image sensor. The polarizing filter has divided areas corresponding to individual pixels of the image sensor, and one area transmits light of a polarization component in a certain direction. The polarizing filter has regions having orthogonal polarization directions of 0 ° and 90 °, and a polarization component in any one direction enters one pixel corresponding to one region. In this way, invisible information based on the polarization component can be obtained by arranging the polarization filter so as to obtain a different polarization component for each pixel.

An optical filter (polarizing filter) having a wire grid polarizer will be described with reference to FIG.
A polarization camera having a configuration in which the polarization filter shown in FIG. 1A is mounted immediately above an image sensor is known. With such a configuration, the camera can acquire not only luminance information and color information but also polarization information. By utilizing the fact that the polarization reflectance of the subject varies depending on the material and shape, it is possible to realize a sensing camera capable of recognizing the edge of a black body or the outline of a transparent body that could not be accurately captured by a conventional camera. In FIG. 1A, La represents incident light, and Lb represents outgoing light.

  The polarizing filter has a polarizing region provided with the polarizer 11 having the wire grid structure shown in FIG. 1B and a non-polarizing region where the wire grid structure is not formed. In the polarization region, polarizers having a plurality of different patterns are arranged for each pixel. The material constituting the wire grid is not particularly limited, and aluminum is mainly used, but gold, silver, tungsten, and the like can also be used.

  As shown in FIG. 1C, linearly polarized light (TM wave) whose electric field is perpendicular to the wire has a small line width in the vibration direction D, so that the movement of free electrons is limited and is transmitted. On the other hand, linearly polarized light (TE wave) whose electric field is horizontal to the wire largely cancels out due to interference between the light wave scattered from the free electron and the incident wave because free electrons can vibrate parallel to the electric field. Apparently 0. As a result, the incident light La transmits only a specific polarized component that differs for each light receiving region 21.

The structure of the polarization camera is shown in FIG.
As illustrated in FIG. 2A, the polarization camera includes an imaging lens 40, an optical filter 10 that is a polarization filter, and an imaging element 20. In order to acquire image information based on polarization information, it is necessary to align and bond the polarization region of the polarization filter and the light receiving region of the image sensor corresponding thereto with high accuracy. That is, as shown in FIG. 2B, the polarizing filter region is located immediately above the corresponding image sensor 20 region.
Of the incident light La, only a polarization component in a certain direction passes through the polarization region having the polarizer 11, is condensed by the microlens 22, passes through the wiring layer 23, and reaches the light receiving region (light receiving unit) 21. Only one polarization component in one direction is incident on one light receiving region 21, and a different polarization component is incident on the adjacent light receiving region 21. Polarization information can be acquired by the amount of light incident on each light receiving region 21.

When the optical filter 10 is bonded onto the image sensor 20, if the filter region is bonded to the pixel in a shifted manner, crosstalk occurs in which part of light enters another adjacent pixel.
The occurrence of crosstalk will be described with reference to FIG.
As shown in FIG. 3A, when the polarizer 11 of the polarization filter is mounted without shifting with respect to the pixel of the image sensor 20, the light receiving region (light receiving part) 21 of the pixel immediately below the filter is specified. Only polarized light Ld in the direction or only non-polarized light Lc that does not transmit through the polarization region is incident.
However, as shown in FIG. 3B, when the polarizer 11 of the polarization filter is mounted in a shifted state, the polarization Lc in the other direction is incident on the light receiving element (pixel) 24 on which only the polarization Ld in a specific direction is originally incident. Crosstalk occurs, and light of different polarization components is mixed in one pixel, so that accurate polarization information cannot be acquired, and the performance of the polarization camera is deteriorated.

  FIG. 4 is a graph showing the relationship between the positional deviation between the optical filter and the image sensor and the polarization contrast. An image sensor having a pixel side size of 4.4 μm and a light receiving part side size of 2 μm has polarization regions in four directions as shown in FIG. 1B, and has a transmittance ratio of TM waves to TE waves of 100: 1. This is a case where a polarizing filter is mounted with a gap of 0 μm and uniform light having a polarization direction of either 0 ° or 90 ° is incident. The incident light is visible light having a wavelength of about 550 nm, the wire grid has a thickness of about 200 nm where the thickness can be ignored, and the change in polarization contrast with increasing deviation is shown in the region where the incident angle is zero.

As shown in FIG. 4, the polarization contrast is about 18 when no crosstalk due to misalignment occurs. Crosstalk occurs with the displacement of the filter, and the polarization contrast decreases. When the deviation is 1.5 μm, the polarization contrast deteriorates to about 6.
Therefore, the image pickup device package of the present invention suppresses misalignment with the image pickup device, reduces crosstalk, and realizes improvement in polarization contrast.

[Image sensor package]
The image pickup device package of the present embodiment has a pixel array that includes a plurality of light receiving elements 24 and an optical filter 10 in which regions having different optical characteristics corresponding to a plurality of pixels are arranged for each of the plurality of pixels. An image sensor 20 that receives light that has passed through the filter 10, and the image sensor 20 has a microlens 22 that condenses the light for each pixel on the surface facing the optical filter 10. The optical filter 10 has an alignment structure in which a concave portion capable of accommodating the microlens 22 is formed on at least a part of a surface facing the microlens 22, and the concave portion of the alignment structure By accommodating the microlens 22, the optical filter 10 and the image sensor 20 are positioned relative to each other.

The alignment structure may be a glass structure or a resin structure. By setting it as the structure which consists of glass, the refractive index of the optical filter 10 does not change front and back. On the other hand, processing is facilitated by adopting a resin structure.
When the region where the alignment structure is provided is small, the degree of freedom in material selection is high.

The recess of the alignment structure can be a spherical surface. By making the concave portion spherical, the gap with the spherical microlens 22 is reduced, and the optical path deviation at the time of hollow bonding can be reduced with high accuracy. The spherical surface of the concave portion and the spherical surface of the microlens 22 may be engaged with each other so that the entire surface is in close contact with each other, or only a part (for example, the outer peripheral portion) abuts, and there is a gap between the spherical surfaces. It may be.
On the other hand, by forming the concave portion of the alignment structure with a non-curved surface, the microlens 22 can be accommodated in the concave portion regardless of the shape of the microlens 22.

  Moreover, the said alignment structure may accommodate the one micro lens 22 in one recessed part, and may accommodate the some micro lens 22 in one recessed part. By forming a concave portion that accommodates the plurality of microlenses 22, processing is facilitated.

  The optical filter 10 may have the alignment structure formed on the entire surface facing the microlens 22. By providing the entire alignment structure, it is possible to correct the misalignment on the entire surface.

  In this embodiment, the region having different optical characteristics is, for example, a region where a polarizer having a plurality of different patterns is disposed for each pixel, a region where a polarizer is not disposed, and a color filter. This is an area where different color filters are arranged for each pixel.

Examples of the polarizer 11 include a wire grid structure and a one-dimensional photonic crystal.
In the aspect in which the optical filter 10 has the polarizer 11 having a wire grid structure, it is possible to cope with a wide wavelength range.
In the aspect in which the optical filter 10 includes the one-dimensional photonic crystal polarizer 11, a high polarization contrast can be realized for incident light in a specific wavelength region.

[First Embodiment]
5 and 6 show examples of the image sensor package according to the first embodiment.
5A is a top view of the polarizer 11 of the optical filter 10, FIG. 5B is a cross-sectional view of the optical filter 10, and FIG. 5C is an explanatory diagram illustrating correction of positional deviation of the image pickup device package. FIG. 6 is a schematic view and a partially enlarged view of the configuration of the image pickup device package.

As described above, when the polarizer 11 that is the polarization region corresponding to the pixel of the image sensor 20 is shifted, crosstalk occurs and the polarization contrast is lowered. A conventional polarizing filter having a wire grid polarizer has a smooth surface because the surface protective layer is formed of SiO ₂ or the like after the wire grid is fabricated. Therefore, the amount of displacement of the optical filter 10 with respect to the image sensor 20 depends on the accuracy of the mounting environment.

On the other hand, in the imaging device package of the present embodiment, as shown in FIG. 5B, the protective layer of the optical filter 10 is provided with an alignment structure in which a recess capable of accommodating the microlens 22 is formed. , The amount of deviation can be reduced.
Specifically, a concave portion having a spherical structure that is paired with the microlens 22 is formed on the glass surface by a method such as gray scale exposure and dry etching.

As shown in FIG. 5C, when the optical filter 10 is pushed down with respect to the image sensor 20 during mounting, the end portion (protruded portion) of the alignment structure 14 and the microlens 22 come into contact with each other. Since the conventional optical filter has a flat opposing surface, it was impossible to push it down further from where it contacted the microlens. However, in the image pickup device package of the present embodiment, by providing the alignment structure 14 in the optical filter 10, it can be further pushed down from the contact state with the microlens 22, and passive positioning using the shape of the microlens 22 is performed. It becomes possible.
FIG. 6 shows a schematic view and a partially enlarged view of the image pickup device package in a positioned state.

[Second Embodiment]
FIG. 7 shows an example of an image sensor package according to the second embodiment.
FIG. 7A is a perspective view schematically showing the structure of one pixel of the optical filter, and FIG. 7B is a schematic view and a partially enlarged view of the configuration of the image sensor package.
As in the first embodiment, the image pickup device package of the present embodiment can be passively positioned using the shape of the microlens 22 by providing the alignment structure 14.
The concave portion of the alignment structure 14 in the present embodiment is configured as a non-curved surface as shown in FIG. 7A, but can be mounted with suppressed displacement as shown in FIG. 7B.

  As described above, the concave portion of the alignment structure 14 is in contact with the surface of the microlens 22 with an angle, and the image pickup element can be used regardless of the shape of the concave portion as long as the shift amount can be corrected by pushing down the optical filter 10. 20 can be suppressed, crosstalk can be reduced, and polarization contrast can be improved.

[Third Embodiment]
FIG. 8 shows an example of an image sensor package according to the third embodiment.
Similar to the first embodiment, the image pickup device package according to the present embodiment can suppress the displacement with respect to the pixels at the time of mounting by providing the alignment structure 14.
In the image pickup device package of the present embodiment, a plurality of microlenses 22 are accommodated in one recess of the alignment structure 14.
Thus, the recesses of the alignment structure 14 do not necessarily have to be provided at the same pitch as the pixels, and may have a structure that accommodates two pixels as shown in FIG.

[Fourth Embodiment]
FIG. 9 shows an example of an image sensor package according to the fourth embodiment.
The image pickup device package of this embodiment has an alignment structure 14 in a part of the optical filter 10.
Since the region of the polarizer 11 of the optical filter 10 is divided at the same size and the same pitch as the pixels of the image sensor 20, if the deviation of the optical filter 10 is zero in any two or more regions, the entire region The shift can be suppressed.
For example, as shown in FIG. 9, by providing the alignment structure 14 only at the end of the optical filter 10, the displacement at the outermost periphery of the effective pixels of the image sensor 20 is suppressed, and as a result, the displacement at the entire surface is suppressed. The polarization contrast is improved.

The image pickup device package of the present invention has the alignment structure 14 in which the optical filter 10 has a recess capable of accommodating the microlens 22, and the optical lens 10 is accommodated in the recess of the alignment structure 14. The structure is not limited to the above-described embodiment as long as it has the principle that the image sensor 20 and the image sensor 20 are positioned relative to each other.
As the imaging device package, for example, a resin sensor package, a ceramic package, or a stacked package can be used.

The method for adhering the positioned optical filter 10 and the image sensor 20 is not particularly limited, and the optical filter 10 and the image sensor 20 can be adhered by a known method.
Further, the protective layer on the wire grid surface of the optical filter 10 is made of a resin having a refractive index close to that of glass instead of SiO ₂ and the alignment structure 14 is formed, so that the same effect can be obtained.

10 Optical filter 11 Polarizer (wire grid)
12 Transparent substrate (glass)
13 Color filter 14 Alignment structure 20 Image sensor (image sensor)
21 Light receiving area 22 Micro lens 23 Wiring layer 24 Light receiving element 30 Imaging element substrate (sensor substrate)
40 Imaging Lens La Incident Light Lb Outgoing Light Lc Transmitted Light (90 ° Polarized)
Ld Transmitted light (45 ° polarization)
D Vibration direction

JP 2010-26175 A

Claims (10)

An optical filter in which regions having different optical characteristics are arranged corresponding to a plurality of pixels;
An image sensor that has a pixel array composed of a plurality of light receiving elements and receives light that has passed through the optical filter;
The imaging device has a microlens array in which microlenses that collect light for each pixel are arranged on the surface facing the optical filter in correspondence with the pixels,
The optical filter has an alignment structure in which a recess capable of accommodating the microlens is formed on at least a part of a surface facing the microlens,
An image pickup device package characterized in that the optical filter and the image pickup device are positioned relative to each other by accommodating the microlens in a concave portion of the alignment structure.   The imaging device package according to claim 1, wherein the alignment structure is made of glass.   The imaging device package according to claim 1, wherein the alignment structure is made of a resin.   The imaging device package according to claim 1, wherein the concave portion of the alignment structure is formed of a spherical surface.   The imaging device package according to claim 1, wherein the concave portion of the alignment structure is formed of a non-curved surface.   The image pickup device package according to claim 1, wherein a plurality of the microlenses are accommodated in one concave portion of the alignment structure.   The image pickup device package according to claim 1, wherein the optical filter has the alignment structure on a whole surface facing the microlens.   The image pickup device package according to claim 1, wherein the optical filter includes a polarizer having a wire grid structure.   The image pickup device package according to claim 1, wherein the optical filter includes a one-dimensional photonic crystal polarizer.   An image pickup apparatus comprising: the image pickup device package according to claim 1; an image pickup lens; and a signal processing unit.