U.S. patent application number 14/714411 was filed with the patent office on 2015-10-22 for solid-state imaging device.
This patent application is currently assigned to Kabushiki Kaisha Toshiba. The applicant listed for this patent is Kabushiki Kaisha Toshiba. Invention is credited to Hideyuki FUNAKI, Hiroto HONDA, Mitsuyoshi KOBAYASHI, Honam KWON, Kazuhiro SUZUKI, Risako UENO.
Application Number | 20150304579 14/714411 |
Document ID | / |
Family ID | 50680782 |
Filed Date | 2015-10-22 |
United States Patent
Application |
20150304579 |
Kind Code |
A1 |
HONDA; Hiroto ; et
al. |
October 22, 2015 |
SOLID-STATE IMAGING DEVICE
Abstract
A solid-state imaging device according to an embodiment
includes: an imaging element including an imaging area formed with
a plurality of pixel blocks each including pixels; a first optical
system forming an image of an object on an imaging surface; and a
second optical system re-forming the image, which has been formed
on the imaging surface, on the pixel blocks corresponding to
microlenses, the second optical system including a microlens array
formed with the microlenses provided in accordance with the pixel
blocks. The microlenses are arranged in such a manner that an angle
.theta. between a straight line connecting center points of
adjacent microlenses and one of a row direction and a column
direction in which the pixels are aligned is expressed as follows:
.theta.>sin.sup.-1(2dp/D.sub.ml), where D.sub.ml represents
microlens pitch, and dp represents pixel pitch.
Inventors: |
HONDA; Hiroto;
(Yokohama-Shi, JP) ; SUZUKI; Kazuhiro; (Tokyo,
JP) ; KOBAYASHI; Mitsuyoshi; (Yokohama-Shi, JP)
; UENO; Risako; (Tokyo, JP) ; KWON; Honam;
(Kawasaki-Shi, JP) ; FUNAKI; Hideyuki; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kabushiki Kaisha Toshiba |
Minato-ku |
|
JP |
|
|
Assignee: |
Kabushiki Kaisha Toshiba
Minato-ku
JP
|
Family ID: |
50680782 |
Appl. No.: |
14/714411 |
Filed: |
May 18, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14077537 |
Nov 12, 2013 |
9064766 |
|
|
14714411 |
|
|
|
|
Current U.S.
Class: |
348/294 |
Current CPC
Class: |
H01L 27/14627 20130101;
H04N 5/2254 20130101; H04N 5/3745 20130101; H04N 5/374 20130101;
H01L 27/14605 20130101; H01L 27/14625 20130101; H04N 5/369
20130101; G02B 13/0085 20130101; H04N 5/347 20130101; G02B 3/0056
20130101; H04N 5/2258 20130101 |
International
Class: |
H04N 5/374 20060101
H04N005/374; H04N 5/347 20060101 H04N005/347; H04N 5/225 20060101
H04N005/225; H04N 5/3745 20060101 H04N005/3745; G02B 3/00 20060101
G02B003/00; G02B 13/00 20060101 G02B013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 13, 2012 |
JP |
2012-249321 |
Claims
1. An imaging device comprising: an imaging element including a
plurality of pixels; an optical system; and a plurality of
microlenses, wherein the plurality of microlenses are arranged in
such a manner that an angle .theta. between a straight line
connecting center points of adjacent microlenses and a first
direction in which the pixels are aligned is expressed as follows:
.theta.>sin.sup.-1(2dp/D.sub.ml) where D.sub.ml represents
microlens pitch, and dp represents pixel pitch.
2. The device according to claim 1, wherein the first direction is
a direction to select the pixels.
3. The device according to claim 1, wherein the first direction is
a direction to read the pixels.
4. The device according to claim 1, wherein the plurality of
microlenses are arranged in a hexagonal closest packed array, and
the angle .theta. is not included in the following ranges:
60.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.60.degree.+sin.-
sup.-1(2dp/D.sub.ml).
5. The device according to claim 1, wherein the plurality of
microlenses are arranged in a square array, and the angle .theta.
is not included in the following ranges:
26.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.26.degree.+sin.-
sup.-1(2dp/D.sub.ml)
45.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.45.degree.+sin.-
sup.-1(2dp/D.sub.ml).
6. The device according to claim 1, further comprising a processing
unit configured to process a signal output from the imaging
element.
7. The device according to claim 1, further comprising a drive unit
configured to drive the imaging element.
8. The device according to claim 1, further comprising a power
supply connected to the imaging element.
9. An imaging device comprising: an imaging element including a
plurality of pixels; an optical system; and a plurality of
microlenses, wherein the plurality of microlenses are arranged in
such a manner that an angle .theta. between a straight line
connecting center points of adjacent microlenses and one of a first
direction and a second direction in which the pixels are aligned is
expressed as follows: .theta.>sin.sup.-1(2dp/D.sub.ml) where
D.sub.ml represents microlens pitch, and dp represents pixel
pitch.
10. The device according to claim 9, wherein the first direction is
a direction to select the pixels.
11. The device according to claim 9, wherein the second direction
is a direction to read the pixels.
12. The device according to claim 9, wherein the plurality of
microlenses are arranged in a hexagonal closest packed array, and
the angle .theta. is not included in the following ranges:
60.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.60.degree.+sin.-
sup.-1(2dp/D.sub.ml).
13. A mobile communication terminal comprising a imaging device,
the imaging device comprising: an imaging element including a
plurality of pixels; an optical system; and a plurality of
microlenses, wherein the plurality of microlenses are arranged in
such a manner that an angle .theta. between a straight line
connecting center points of adjacent microlenses and one of a first
direction and a second direction in which the pixels are aligned is
expressed as follows: .theta.>sin.sup.-1(2dp/D.sub.ml) where
D.sub.ml represents microlens pitch, and dp represents pixel
pitch.
14. The terminal according to claim 13, wherein the first direction
is a direction to select the pixels.
15. The terminal according to claim 13, wherein the second
direction is a direction to read the pixels.
16. The terminal according to claim 13, wherein the plurality of
microlenses are arranged in a hexagonal closest packed array, and
the angle .theta. is not included in the following ranges:
60.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.60.degree.+sin.-
sup.-1(2dp/D.sub.ml).
17. A digital camera comprising a imaging device, the imaging
device comprising: an imaging element including a plurality of
pixels; an optical system; and a plurality of microlenses, wherein
the plurality of microlenses are arranged in such a manner that an
angle .theta. between a straight line connecting center points of
adjacent microlenses and one of a first direction and a second
direction in which the pixels are aligned is expressed as follows:
.theta.>sin.sup.-1(2dp/D.sub.ml) where D.sub.ml represents
microlens pitch, and dp represents pixel pitch.
18. The camera according to claim 17, wherein the first direction
is a direction to select the pixels.
19. The camera according to claim 17, wherein the first direction
is a direction to read the pixels.
20. The camera according to claim 17, wherein the plurality of
microlenses are arranged in a hexagonal closest packed array, and
the angle .theta. is not included in the following ranges:
60.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.60.degree.+sin.-
sup.-1(2dp/D.sub.ml).
21. A surveillance camera comprising a imaging device, the imaging
device comprising: an imaging element including a plurality of
pixels; an optical system; and a plurality of microlenses, wherein
the plurality of microlenses are arranged in such a manner that an
angle .theta. between a straight line connecting center points of
adjacent microlenses and one of a first direction and a second
direction in which the pixels are aligned is expressed as follows:
.theta.>sin.sup.-1(2dp/D.sub.ml) where D.sub.ml represents
microlens pitch, and dp represents pixel pitch.
22. The camera according to claim 21, wherein the first direction
is a direction to select the pixels.
23. The camera according to claim 21, wherein the first direction
is a direction to read the pixels.
24. The camera according to claim 21, wherein the plurality of
microlenses are arranged in a hexagonal closest packed array, and
the angle .theta. is not included in the following ranges:
60.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.60.degree.+sin.-
sup.-1(2dp/D.sub.ml).
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of and claims the benefit
of priority under 35 U.S.C. .sctn.120 from U.S. Ser. No. 14/077,537
filed Nov. 12, 2013, and claims the benefit of priority under 35
U.S.C. .sctn.119 from Japanese Patent Application No. 2012-249321
filed Nov. 13, 2012, the entire contents of each of which are
incorporated herein by reference.
FIELD
[0002] Embodiments described herein relate generally to solid-state
imaging devices.
BACKGROUND
[0003] In recent years, CMOS image sensors have been actively
developed. Particularly, as miniaturization (according to a design
rule for miniaturization) is progressing in semiconductor
processes, single-panel color image sensors with more than 10
million pixels at pixel pitch of 1.4 .mu.m, for example, are
already available on the market. In the trend of the increasing
numbers of pixels, attempts are being made to obtain physical
information that has not been obtained due to the use of a large
number of pixels, such as a distance to an object.
[0004] There has been a known imaging element that obtains
information about the distance from the imaging element to an
object by inserting a microlens array as a compound-eye optical
system between the imaging lens and the imaging sensor. However,
with this imaging element, the S/N ratio and the resolution of an
image cannot be restored satisfactorily when the single image is
re-formed by combining images formed by respective microlenses.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIGS. 1A and 1B are diagrams showing a solid-state imaging
device according to an embodiment;
[0006] FIG. 2 is a diagram showing a microlens array that is a
hexagonal closest packed array used in the solid-state imaging
device of the embodiment;
[0007] FIG. 3 is a diagram showing a microlens array that is a
square array used in the solid-state imaging device of the
embodiment;
[0008] FIG. 4 is a diagram for explaining image overlaps that
appear when the imaging magnification N is 0.5;
[0009] FIG. 5 is a diagram for explaining image overlaps and added
portions;
[0010] FIG. 6 is a diagram for explaining the condition for two
overlapping pixels to exist in the same row;
[0011] FIG. 7 is a diagram for explaining angles .theta. that
should be avoided in a hexagonal closest packed array;
[0012] FIG. 8 is a diagram for explaining angles .theta. that
should be avoided in a square array;
[0013] FIG. 9 is a diagram showing example angles .theta. that
should be avoided in a hexagonal closest packed array;
[0014] FIG. 10 is a diagram showing example angles .theta. that
should be avoided in a square array; and
[0015] FIG. 11 is a block diagram showing a solid-state imaging
device according to another embodiment.
DETAILED DESCRIPTION
[0016] A solid-state imaging device according to an embodiment
includes: an imaging element including an imaging area formed with
a plurality of pixel blocks each including a plurality of pixels; a
first optical system configured to form an image of an object on an
imaging surface; and a second optical system configured to re-form
the image, which has been formed on the imaging surface, on the
plurality of pixel blocks corresponding to a plurality of
microlenses, the second optical system including a microlens array
formed with the plurality of microlenses provided in accordance
with the plurality of pixel blocks. The plurality of microlenses
are arranged in such a manner that an angle .theta. between a
straight line connecting center points of adjacent microlenses and
one of a row direction and a column direction in which the pixels
are aligned is expressed as follows:
.theta.>sin.sup.-1(2dp/D.sub.ml)
where D.sub.ml represents microlens pitch, and dp represents pixel
pitch.
[0017] The following is a detailed description of embodiments, with
reference to the accompanying drawings.
[0018] FIG. 1A shows a solid-state imaging device according to an
embodiment. The solid-state imaging device of this embodiment
includes an imaging optical system (an imaging lens) 10, an optical
system including a microlens array 20 having microlenses arranged
in an array, and an imaging element 30. The imaging element 30
includes an imaging area having pixel blocks each including pixels.
Each of the pixel blocks has pixels arranged in the X-axis
direction and the Y-axis direction in an array. The imaging optical
system 10 forms an image of an object 100 on a virtual imaging
surface 70. The optical system including the microlens array 20 has
microlenses provided in accordance with the above mentioned pixel
blocks, and re-forms the image, which has been formed on the above
described virtual imaging surface 70, on the pixel blocks
corresponding to the respective microlenses.
[0019] FIG. 1B shows the shift lengths of image points of the same
object in the optical system (a virtual image optical system) of
the solid-state imaging device according to this embodiment.
[0020] When attention is paid only to the imaging optical system
(the imaging lens 10), the principal ray and its family of rays
from the object 100 form an image on the virtual imaging surface 70
determined by the focal length of the imaging optical system 10 and
the distance from the object 100, so as to satisfy the relationship
expressed by the equation (1).
1 f = 1 A + 1 B ( 1 ) ##EQU00001##
[0021] Here, f represents the focal length of the imaging lens 10,
A represents the distance from the object-side principal surface of
the imaging lens 10 to the object 100, and B represents the
distance from the image-side principal surface of the imaging lens
10 to the virtual imaging surface 70. The magnification (the
lateral magnification) of the imaging lens 12 is expressed by the
following equation (2).
M = B A ( 2 ) ##EQU00002##
[0022] In this embodiment, the virtual imaging surface 70 of the
imaging lens 10 is located behind the imaging element 30 (or on the
opposite side of the imaging lens 10 from the object 100). At this
point, the microlens array (hereinafter also referred to as ML) 20
is located in front of the virtual imaging surface 70, and
therefore, light is collected on the surface of the imaging element
30 that has pixels arranged in front of the virtual imaging surface
70 in practice. As a result, the light rays form a reduced image
compared with the virtual image. The microlens imaging system
forming the microlens array 20 is expressed by the following
equation (3).
1 g = 1 C + 1 D ( 3 ) ##EQU00003##
[0023] Here, g represents the focal length of the microlenses, C
represents the distance from the object-side principal surface of
the microlenses to the virtual imaging surface 70, and D represents
the distance from the image-side principal surface of the
microlenses to the surface of the imaging element 30. At this
point, the magnification of the microlens imaging system is
expressed by the following equation (4).
N = D C ( 4 ) ##EQU00004##
[0024] Here, the variable E shown in the equation (5) in terms of a
geometric relationship is introduced. When the optical system is a
fixed focus optical system, the variable E is a fixed set
value.
E=B-C (5)
[0025] Here, D.sub.ML represents the alignment pitch of microlenses
14 or the distance between the microlenses in a case where two
adjacent microlenses are selected. At this point, light rays 84a,
84b, 84c, and 86 emitted from the same object form images at the
adjacent microlenses 14 independently of one another. The distance
D.sub.ML and the image shift length .DELTA. on one side are
expressed by the equation (6) in terms of the geometric
relationship among the principal rays 84a, 84b, and 84c at the
respective microlenses shown in FIG. 1B.
C D ML = D .DELTA. ( 6 ) ##EQU00005##
[0026] With the above parameters, the changes in the respective
parameters with respect to movements (changes in A) of the object
100 are expressed. Where A.sub.0 represents the distance from the
imaging lens 10 to the object that can be imaged, each parameter
having a subscript 0 to the right thereof (B.sub.0, C.sub.0,
D.sub.0, and .DELTA..sub.0) represents a value that is achieved
when the distance to the object is A.sub.0. When A.sub.0 is
determined, each of the above mentioned parameters is uniquely
determined in a fixed focus optical system.
[0027] Here, M (imaging lens magnification) represents the change
in the parameter D that is observed when the distance from the
imaging lens 10 to the object 100 changes from A.sub.0 to A.
According to the equations (1) through (5), the imaging lens
magnification M has the relationship expressed in the equation
(7).
D = ( 1 g + 1 C ) - 1 = ( 1 g + 1 ( B - E ) ) - 1 = ( 1 g + 1 B - (
B 0 - C 0 ) ) - 1 = ( 1 g - 1 - D 0 N 0 + ( M 0 - M ) f ) - 1 ( 7 )
##EQU00006##
[0028] Also, according to the equations (1), (2), (6), and (7), the
distance A from the imaging lens 10 to the object 100, the shift
length .DELTA., and the magnification M have the relationship
expressed in the following equation (8).
A = ( 1 f - 1 B ) - 1 = ( 1 f - 1 B 0 - C 0 + C ) - 1 = ( 1 f - 1 (
M 0 + 1 ) f - D 0 N 0 + D ML D .DELTA. ) - 1 ( 8 ) ##EQU00007##
[0029] That is, the distance between the object 100 and the imaging
lens 10 can be determined from the image shift length .DELTA..
[0030] In a case where the microlens array 20 is not provided, and
the imaging element 30 is located on the virtual imaging surface
70, an image of the object is formed on the virtual imaging surface
70. In a case where light rays emitted from the same object are
divided by microlenses, and images are formed on the surface of the
imaging element 30 located in front of the virtual imaging surface
70 as in this embodiment, the same object is imaged more than once
in accordance with parallaxes. Accordingly, images formed by the
microlenses imaging the same object more than once (microlens
images) are output as an image.
[0031] The microlens images are images formed when the microlenses
are arranged at regular pitch. The microlens images are reduced
from the image, which should have been formed on the virtual
imaging surface 70, by the magnification N (according to the
equation (4)) of the microlens imaging system. The obtained
microlens images are re-formed as a two-dimensional image without
an overlapping portion, by subjecting the read image data of each
microlens to a re-forming operation. The re-forming operation will
be described later.
[0032] Having parallaxes smaller than the aperture of the imaging
lens 10, the obtained microlens images can be subjected to a
three-dimensional processing operation that uses parallaxes.
[0033] FIGS. 2 and 3 show plane arrangement methods that can be
used for the microlens array 20 in this embodiment. FIG. 2 is a
diagram showing an example case where the microlenses 21 of the
microlens array 20 are arranged in a hexagonal closest packed
array, and FIG. 3 is a diagram showing an example case where the
microlenses 21 of the microlens array 20 are squarely arranged. The
distance between the centers 211 of the microlenses 21 is
represented by D.sub.ml.
[0034] Here, the microlens array 20 is placed on the image entering
side of the imaging element 30. When the components are stacked on
a plane surface, an angle .theta. is the angle between the X-axis
representing one direction in which the pixels 31 are aligned, and
the X'-axis of the microlens array 20 defined by a straight line
connecting the centers 211 of microlenses 21.
[0035] Referring now to FIG. 4, a method of re-forming a
two-dimensional image without any overlapping portion from
microlens images formed by repeatedly imaging the same object is
described.
[0036] FIG. 4 shows an example case where first through third
microlenses are adjacent to one another, and form microlens images
91a, 91b, and 91c, respectively, on the surface of the imaging
element 30. The visual fields in which the microlens images 91a,
91b, and 91c are formed are visual fields 93a, 93b, and 93c that
overlap with one another on the virtual imaging surface 70. FIG. 4
illustrates a case where the reduction rate N is 0.5. As a result
of enlarging each visual field by 0.5, each object point is imaged
two or more times. When the reduction ratio N is 0.5, the image on
the virtual imaging surface 70 can be reproduced by enlarging each
microlens image by 1/N (=2, when N=0.5). In FIG. 4, reference
numeral 92a indicates the image center of the first microlens, and
reference numeral 94a indicates the center of the visual field of
the first microlens on the virtual imaging surface 70.
[0037] In this embodiment, overlapping portions of the visual
fields are processed by subjecting the luminance values output from
the pixels to an averaging operation. In this manner, one image can
be re-formed from data that has overlapping portions.
[0038] FIG. 5 shows overlaps in the image data of the respective
microlenses at the time of image re-formation. The seven circles
represent the image areas subjected to an enlarging operation that
is performed mainly on the center of each microlens image. For
example, shaded portions 96a and 96b are the overlapping portions
of the microlens image data in this case. At the overlapping
portions, the corresponding two or three sets of image data is
subjected to averaging, to form a single image. In the process of
averaging, the random noise in each microlens image is effectively
reduced.
[0039] Normally, when random noises having no correlation with one
another are subjected to averaging N times, the standard deviation
of noise becomes 1/N.sup.1/2. Therefore, as the number N of
overlaps becomes larger, the reduction in image noise becomes
larger.
[0040] However, when random noises having a correlation with one
another are subjected to averaging, noises are not reduced. For
example, if there are horizontal linear noises in FIG. 5, the added
microlens images have common horizontal linear noises at the added
portions 96a and 96b that are the shaded portions in the drawing.
Therefore, a noise reduction effect cannot be expected.
[0041] In an image element, pixels are normally selected in order
of row number, and columns are normally read in parallel.
Therefore, horizontal linear noises or vertical linear noises are
liable to appear.
[0042] In a case where the added microlens images have common
horizontal or vertical linear noises, a straight line connecting
the centers of microlenses coincides with the X-axis direction or
the Y-axis direction formed by the pixel array of the imaging
element 30. Referring now to FIG. 6, the condition for the axis
directions to match is described.
[0043] FIG. 6 shows three microlenses 211, 212, and 213. The grids
represent the pixel array. Here, the straight line connecting the
centers of the microlenses forms an angle .theta. with the
horizontal axis of the pixels. The center-to-center distance
between the microlenses (the microlens pitch) is represented by
D.sub.ml, and the pixel pitch is represented by dp. If the pixel
pitch in the X-direction and the pixel pitch in the Y-direction
differ from each other, the pitch in the Y-direction is represented
by dp. For example, pixels 221 and 222 exist in the microlenses 211
and 212, and are located on the straight line connecting the
centers of the microlenses 211 and 212. If the distance between the
pixels 221 and 222 is 1/2.times.D.sub.ml, the microlens images at
these pixels overlap with each other and are added when each of the
microlens images is enlarged by 2 (=1/N). The condition for the
pixel 221 and the pixel 222 to be located in different rows from
each other at this point is expressed as follows.
1/2.times.D.sub.ml.times.sin .theta.>dp (9)
[0044] If D.sub.ml/dp is 20, for example, sin .theta. should be
greater than 0.1. Accordingly, when the angle .theta. is not
smaller than -sin.sup.-1(0.1) and not larger than sin.sup.-1(0.1),
the pixels might not overlap with each other. The reason that the
distance between the pixels is assumed to be 1/2.times.D.sub.ml is
that pixels located at a distance of 1/2.times.D.sub.ml or longer
from each other often overlap with each other.
[0045] Referring now to FIGS. 7 and 8, angles .theta. that should
be avoided are described. FIG. 7 shows a microlens array that is a
hexagonal closest packed array. First, straight lines connecting
the centers of microlenses are described. Where the direction in
which microlenses are aligned at the highest density is the
direction at 0.degree., the above described noise reduction effect
cannot be expected when the axis in the horizontal direction of the
pixel array coincides with the direction at 0.degree.. The same
applies in cases where the angle .theta. is 30.degree. and
60.degree., as shown in FIG. 7. For example, in cases where the
0.degree. axis of the microlens array forms an angle of 15.degree.
with the horizontal axis of the pixels, pixels in different rows
overlap with each other and are added. Therefore, such cases are
preferable.
[0046] As can be seen from FIG. 8, in a square array, the above
mentioned noise reduction effect cannot be expected when the angle
.theta. is 0.degree., 26.degree., or 45.degree..
[0047] FIG. 9 shows the angles .theta. that should be avoided in a
hexagonal closest packed array. In FIG. 9, angles are determined,
with dp/D.sub.ml being equal to 1/20. The error bars indicate the
conditions for two pixels located at a distance of
1/2.times.D.sub.ml from each other to exist in the same row. When
the target microlens is to overlap with a microlens that is located
one microlens outside, the error bars indicate the ranges of angles
.theta. expressed as follows according to the equation (9).
1/2.times.D.sub.ml.times.sin .theta..ltoreq.dp
[0048] That is, in the case of a hexagonal closest packed array,
the angles .theta. to be avoided are expressed as follows.
-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.sin.sup.-1(2dp/D.sub.ml)
30.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.30.degree.+sin-
.sup.-1(2dp/D.sub.ml)
60.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.60.degree.+sin-
.sup.-1(2dp/D.sub.ml)
[0049] FIG. 10 shows the angles .theta. to be avoided in a case
where the microlenses are squarely arranged. In FIG. 10, angles are
determined, with dp/D.sub.ml being equal to 20. In the case of a
square array, the angles .theta. to be avoided are expressed as
follows.
-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.sin.sup.-1(2dp/D.sub.ml)
26.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.26.degree.+sin-
.sup.-1(2dp/D.sub.ml)
45.degree.-sin.sup.-1(2dp/D.sub.ml).ltoreq..theta..ltoreq.45.degree.+sin-
.sup.-1(2dp/D.sub.ml)
[0050] As described above, the microlenses are arranged so that the
axis formed by a straight line connecting the centers of
microlenses forms a constant angle with the horizontal axis of
pixels. In this manner, a low noise solid-state imaging device can
be realized.
[0051] As described so far, this embodiment can provide a
solid-state imaging device that can restore the S/N ratio and the
resolution of an image even when the image is re-formed.
[0052] This embodiment can also provide a solid-state imaging
device that can obtain distance information and improve SNR,
without false color generation at the time of imaging of an object
at high spatial frequency.
[0053] As shown in FIG. 11, any of the above described solid-state
imaging devices may include a drive unit 300 that drives the
imaging element 30, and a processing unit 320 that processes
signals output from the imaging element 30. Any of the above
described solid-state imaging devices may also include a power
supply 330 that is necessary for driving the imaging element 30.
Any of the above described solid-state imaging devices may also
include an output unit 340 such as a display. An output device (not
shown) that is provided outside may be connected to the solid-state
imaging device. Each signal output from the imaging element 30 is
displayed by the output unit 340 or the output device.
[0054] Any of the above described solid-state imaging devices may
be a mobile communication terminal, a digital camera, a personal
computer, or a surveillance camera, for example.
[0055] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the inventions. Indeed, the novel
methods and systems described herein may be embodied in a variety
of other forms; furthermore, various omissions, substitutions and
changes in the form of the methods and systems described herein may
be made without departing from the spirit of the inventions. The
accompanying claims and their equivalents are intended to cover
such forms or modifications as would fail within the scope and
spirit of the inventions.
* * * * *