JP2007155929A - Solid-state imaging element and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging element capable of reducing degradation in the image quality of a picked up image while avoiding a decrease in numerical aperture and hence sensitivity by eliminating the need to dispose a plurality of photo-electric conversion parts within a pixel on the assumption that the solid-state imaging element also functions as a focal point detecting element, and to provide an imaging apparatus using the solid-state imaging element. <P>SOLUTION: One focusing detection area 12 of the solid-state imaging element 2 includes: a plurality of first pixels 20 that receive and photo-electrically convert a luminous flux from the first area of the exit pupil of an imaging lens which is not substantially eccentric from the center of the exit pupil; and a plurality of second pixels 21(L) that are in the second area of the exit pupil substantially forming part of the first area and selectively receive and photo-electrically convert a luminous flux from the second area of the exit pupil eccentric in a predetermined direction from the center of the exit pupil. The first pixels 20 are used to obtain a pickup image. The second pixels 21(L) and the first pixels 20 in the vicinity of them are used to detect a focal point. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device and an imaging apparatus using the same.

  In recent years, imaging devices such as video cameras and digital still cameras have been widely used. In these cameras, a solid-state imaging device such as a CCD type or a CMOS type is used. In these solid-state imaging devices, a plurality of pixels having a photoelectric conversion unit that generates a signal charge according to the amount of incident light are arranged in a matrix.

  A microlens is disposed on-chip on the light incident side of the photoelectric conversion unit. Light incident on the pixel portion other than the photoelectric conversion portion does not contribute to the image signal and is wasted. The microlens is disposed in order to condense the light thus wasted on the photoelectric conversion unit, increase the light use efficiency, and increase the amount of light. In order to obtain a color image, a color filter is disposed on the photoelectric conversion unit. As a combination of color filters, a system using R, G, and B or a complementary color system is used. As the arrangement of the color filters, a Bayer arrangement, a stripe arrangement, and the like are well known.

  By the way, in an imaging apparatus such as a camera, it is necessary to detect the focus adjustment state of the photographing lens in order to realize automatic focus adjustment. Conventionally, a focus detection element has been provided separately from the solid-state imaging element. However, in that case, the cost increases or the size of the apparatus increases by the amount of the focus detection element and the focus detection optical system that guides light to the focus detection element.

  Therefore, in recent years, a so-called pupil division phase difference method (sometimes called a pupil division method or a phase difference method) is adopted as a focus detection method, and solid-state imaging configured to be used as a focus detection element. Elements have been proposed (for example, Patent Documents 1 and 2 below).

  In addition to a plurality of imaging pixels, the solid-state imaging device disclosed in Patent Document 1 includes a plurality of first focus detection pixels (pixels denoted by reference sign “S1” in Patent Document 1) and a plurality of first imaging pixels. 2 focus detection pixels (pixels to which “S2” is attached in Patent Document 1). As shown in FIG. 3 and FIG. 4 of Patent Document 1, each pixel includes a microlens provided on the photoelectric conversion unit in a one-to-one relationship with the pixel. A light shielding film is provided near the focal plane of the microlens between the microlens and the photoelectric conversion unit, and an opening is provided in the light shielding film for each of the first and second focus detection pixels. Yes. Therefore, since the distance between the exit pupil of the photographic lens and the microlens is sufficiently long with respect to the size of the microlens, the light-shielding film is substantially imaged with the exit pupil of the photographic lens by the microlens (that is, It is arranged at a position that is substantially conjugate). In the imaging pixel, such a light shielding film is not provided, or an opening that is not biased with respect to the optical center of the microlens is provided in the light shielding film. As a result, the imaging pixel receives and photoelectrically converts a light beam from the exit pupil region that is not decentered from the center of the exit pupil of the photographing lens. In the first focus detection pixel, the opening of the light shielding film is arranged so as to be biased with respect to the optical center of the microlens. In the second focus detection pixel, the opening of the light shielding film is located at the optical center of the microlens. On the other hand, the first focus detection pixels are arranged so as to be biased in the opposite direction. Thus, the first focus detection pixel selectively receives and photoelectrically converts a light beam from a partial region of the exit pupil of the photographing lens and decentered in a predetermined direction from the center of the exit pupil. It will be. The first focus detection pixel selectively receives and photoelectrically converts a light beam from a partial region of the exit pupil of the photographing lens and decentered in the opposite direction from the center of the exit pupil. become. In the solid-state imaging device disclosed in Patent Document 1, a color filter is provided in the imaging pixel. However, as illustrated in FIGS. 3 and 4 of Patent Document 1, the first and second pixels are used. These focus detection pixels are not provided with a color filter.

  In Patent Document 1, in accordance with the principle of the pupil division phase difference method, a signal output from the connection of the plurality of first focus detection pixels and a connection of the plurality of second focus detection pixels is output. It is described that the focus adjustment state of the optical system can be detected from the phase difference with the signal. At this time, the signal of the imaging pixel is not used at all for detecting the focus adjustment state. The first and second focus detection pixels are used only for focus detection. When an image is captured after the photographing lens is focused, the first and second focus detection pixels in the image signal are used. For example, a signal obtained by performing interpolation processing from signals of the surrounding imaging pixels is used as the pixel signal at the position.

  Further, in the solid-state imaging device disclosed in FIG. 12 of Patent Document 2, each pixel of all the pixels is divided into two photoelectric conversion units and pixels on the two divided photoelectric conversion units. A microlens provided in a one-to-one relationship is provided. The two-divided photoelectric conversion unit is disposed at a position that is substantially image-formed (ie, substantially conjugate) with the exit pupil of the photographing lens by the microlens. Therefore, since the distance between the exit pupil of the photographing lens and the microlens is sufficiently long with respect to the size of the microlens, the two-divided photoelectric conversion unit is disposed on the substantially focal plane of the microlens. It will be. From the relationship described above, in each pixel, one part of the photoelectric conversion unit divided into two is a light beam from a region that is a part of the exit pupil of the photographing lens and decentered in a predetermined direction from the center of the exit pupil. Is selectively received and photoelectrically converted. Further, in each pixel, the other part of the photoelectric conversion unit divided into two is selectively a light beam from a region that is a part of the exit pupil of the photographing lens and decentered in the opposite direction from the center of the exit pupil. Light is received and photoelectrically converted. Note that in the solid-state imaging device disclosed in FIG. 12 of Patent Document 2, all pixels are provided with color filters.

  In the solid-state imaging device disclosed in FIG. 12 of Patent Document 2, at the time of focus detection, the signal of one part and the signal of the other part of the two-part photoelectric conversion unit of each pixel are transferred to the floating diffusion at different timings. Are read out individually. Then, according to the principle of the pupil division phase difference method, the focus adjustment state of the photographing lens is detected based on these signals. On the other hand, when an image is captured after the photographing lens is focused, signals from both parts of the two-part photoelectric conversion unit of each pixel are transferred to the same floating diffusion at the same timing, and both signals are added in the pixel. And read.

1 to 10 of Patent Document 2 disclose a solid-state image sensor obtained by modifying the solid-state image sensor disclosed in FIG. 12 of Patent Document 2 as follows. That is, in the solid-state imaging device disclosed in FIGS. 1 to 10 of Patent Document 2, only some of the pixels are divided into two photoelectric conversion units, while the remaining pixels are divided into photoelectric conversion units. It is assumed that no color filter is formed on a pixel in which the photoelectric conversion unit is divided into two, while a color filter is not formed on a pixel in which the photoelectric conversion unit is not divided in two. With this solid-state imaging device, at the time of focus detection, the signal of one part and the signal of the other part of the two-divided photoelectric conversion unit of each pixel having the two-divided photoelectric conversion unit are individually read out. Then, according to the principle of the pupil division phase difference method, the focus adjustment state of the photographing lens is detected based on these signals.
Japanese Patent No. 3592147 JP 2003-244712 A

  However, in the solid-state imaging device disclosed in Patent Document 1, the first and second focus detection pixels are used only for focus detection and cannot be used during image capture. The same state as the pixel defect is caused by the two focus detection pixels, and the image quality of the captured image is inevitably deteriorated although interpolation processing is performed.

  On the other hand, in the solid-state image sensor disclosed in FIG. 12 of Patent Document 2 and the solid-state image sensor disclosed in FIGS. 1 to 10 of Patent Document 2, a pixel having a two-divided photoelectric conversion unit at the time of image capturing. With respect to, since signals from both parts of the two-divided photoelectric conversion unit are added and read within the pixel, deterioration of image quality due to a state similar to a pixel defect can be avoided. However, in these solid-state imaging devices, a plurality of transfer units are provided in one pixel so that signals from both parts of the two-part photoelectric conversion unit in the pixel having the two-part photoelectric conversion unit can be read independently. Since it must be provided, the aperture ratio of the photoelectric conversion unit is lowered, and as a result, the sensitivity is lowered.

  The present invention has been made in view of such circumstances, and on the premise that it also has a function as a focus detection element, the aperture ratio is reduced by not providing a plurality of photoelectric conversion units in one pixel. Another object of the present invention is to provide a solid-state imaging device capable of reducing deterioration in image quality of a captured image while avoiding a sensitivity decrease associated therewith, and an imaging apparatus using the same.

  In order to solve the above-described problem, the solid-state imaging device according to the first aspect of the present invention is a solid-state imaging device that photoelectrically converts a subject image formed by an optical system, and is substantially from the center of the exit pupil of the optical system. A plurality of first pixels that receive and photoelectrically convert a light beam from the first region of the exit pupil that is not decentered, and a second of the exit pupil that substantially forms part of the first region. A plurality of second pixels that selectively receive and photoelectrically convert a light beam from a second region of the exit pupil that is decentered in a predetermined direction from the center of the exit pupil. The first pixel is used to obtain an electrical signal indicating an image corresponding to the subject image, and the first pixel in the vicinity of the plurality of second pixels of the plurality of first pixels, and The plurality of second pixels have an electric power for detecting a focus adjustment state of the optical system. And it is used to obtain the signal.

  The solid-state imaging device according to a second aspect of the present invention is the first aspect, wherein the first pixel and the plurality of second pixels in the vicinity of the plurality of second pixels among the plurality of first pixels. In the one focus detection region including the pixels, a third region of the exit pupil that substantially forms a part of the first region and is opposite to the predetermined direction from the center of the exit pupil It does not include a pixel that selectively receives a light beam from the third region of the exit pupil that is decentered in the direction and performs photoelectric conversion.

  In the solid-state imaging device according to the third aspect of the present invention, in the first or second aspect, the second region is an approximately half region of the first region.

  The solid-state imaging device according to a fourth aspect of the present invention is the solid-state imaging device according to any one of the first to third aspects, wherein the second pixel has a photoelectric conversion unit having the same size as the first pixel. The photoelectric conversion part of the second pixel is partially shielded by the light shielding part, so that the second pixel selectively receives the light flux from the second region of the exit pupil.

  The solid-state imaging device according to a fifth aspect of the present invention is the solid-state imaging device according to any one of the first to third aspects, wherein the second pixel has a photoelectric conversion unit smaller than the first pixel, so that the emission is performed. The light beam from the second region of the pupil is selectively received.

  In the solid-state imaging device according to the sixth aspect of the present invention, in any one of the first to fifth aspects, a color filter is formed in the plurality of first pixels, and the plurality of second pixels includes A color filter is not formed.

  According to a seventh aspect of the present invention, there is provided an imaging apparatus including: a solid-state imaging device according to any one of the first to sixth aspects; and a plurality of second pixels in the vicinity of the plurality of second pixels among the plurality of first pixels. And a detection processing unit that outputs a detection signal indicating a focus adjustment state of the optical system based on a signal from one pixel and signals from the plurality of second pixels.

  The imaging device according to an eighth aspect of the present invention is the imaging device according to the seventh aspect, wherein the detection processing unit starts with a first pixel in the vicinity of the plurality of second pixels among the plurality of first pixels. And a plurality of virtual third pixels that are paired with the plurality of second pixels based on signals from the plurality of second pixels and substantially the same as the first region. And selectively receiving a light beam from the third region of the exit pupil that is eccentric from the center of the exit pupil in a direction opposite to the predetermined direction. A correspondence signal acquisition unit that obtains a signal corresponding to signals from a plurality of virtual third pixels to be converted is included.

  The imaging device according to a ninth aspect of the present invention is the imaging device according to the eighth aspect, wherein the detection processing unit is configured to output the signals from the plurality of second pixels and the virtual plurality obtained by the corresponding signal acquisition unit. And a signal output by the connection of the plurality of second pixels and a signal output by the connection of the virtual plurality of third pixels based on the signal corresponding to the signal from the third pixel Means for obtaining a detection signal indicating the focus adjustment state of the optical system from the phase difference.

  A solid-state imaging device according to a tenth aspect of the present invention is a solid-state imaging device that photoelectrically converts a subject image formed by an optical system, and the exit that is not substantially decentered from the center of the exit pupil of the optical system. A plurality of first pixels that receive and photoelectrically convert a light beam from a first region of the pupil, and a second region of the exit pupil that substantially forms part of the first region, the exit One or more second pixels that selectively receive and photoelectrically convert a light beam from the second region of the exit pupil that is decentered in the predetermined direction from the center of the pupil, and substantially one of the first regions. And selectively receiving a light beam from the third region of the exit pupil that is eccentric from the center of the exit pupil in a direction opposite to the predetermined direction. One or more third pixels to be converted, and the plurality of first pixels are the subject Used to obtain an electrical signal indicating an image corresponding to an image, and is provided in the vicinity of the one or more second pixels and the one or more third pixels of the plurality of first pixels. The first pixel, the one or more second pixels, and the one or more third pixels are used to obtain an electrical signal for detecting a focus adjustment state of the optical system. .

  The solid-state imaging device according to an eleventh aspect of the present invention is the solid-state imaging device according to the tenth aspect, wherein the second region is a substantially half region of the first region.

  In the solid-state imaging device according to a twelfth aspect of the present invention, in the tenth or eleventh aspect, the third region is a substantially half region of the first region.

  In a solid-state imaging device according to a thirteenth aspect of the present invention, in any one of the tenth to twelfth aspects, the second pixel has a photoelectric conversion unit having the same size as the first pixel. The photoelectric conversion part of the second pixel is partially shielded by the light shielding part, so that the second pixel selectively receives the light flux from the second region of the exit pupil.

  The solid-state imaging device according to a fourteenth aspect of the present invention is the solid-state imaging device according to any one of the tenth to thirteenth aspects, wherein the third pixel has a photoelectric conversion unit having the same size as the first pixel. The photoelectric conversion part of the three pixels is partially shielded by the light shielding part, so that the third pixel selectively receives the light flux from the third region of the exit pupil.

  The solid-state imaging device according to a fifteenth aspect of the present invention is the solid-state imaging device according to any one of the tenth to twelfth aspects, wherein the second pixel has a photoelectric conversion unit smaller than the first pixel, so that the emission is performed. The light beam from the second region of the pupil is selectively received.

  According to a sixteenth aspect of the present invention, in any one of the tenth to twelfth and fifteenth aspects, the third pixel has a photoelectric conversion unit smaller than the first pixel. The light beam from the third region of the exit pupil is selectively received.

  In the solid-state imaging device according to a seventeenth aspect of the present invention, in any one of the tenth to sixteenth aspects, a color filter is formed in the plurality of first pixels, and the one or more second pixels In addition, a color filter is not formed on the one or more third pixels.

  An imaging apparatus according to an eighteenth aspect of the present invention is the vicinity of the solid-state imaging element according to any one of the tenth to seventeenth aspects and the one or more second pixels of the plurality of first pixels. And a signal from a first pixel in the vicinity of the one or more third pixels, a signal from the one or more second pixels, and a signal from the one or more third pixels. And a detection processing unit that outputs a detection signal indicating a focus adjustment state of the optical system.

  The imaging device according to a nineteenth aspect of the present invention is the imaging device according to the eighteenth aspect, wherein the detection processing unit is a first one in the vicinity of the one or more second pixels of the plurality of first pixels. One or more virtual third pixels paired with the one or more second pixels based on a signal from the pixel and a signal from the one or more second pixels, the emission A first corresponding signal acquisition unit that obtains a signal corresponding to a signal from one or more virtual third pixels that selectively receive and photoelectrically convert a light beam from the third region of the pupil; One or more third pixels based on a signal from a first pixel in the vicinity of the one or more third pixels of the first pixel and a signal from the one or more third pixels. One or more virtual second pixels that form a pair with the three pixels, the luminous flux from the second region of the exit pupil By receiving the 択的 those comprising a second corresponding signal acquisition unit for obtaining a signal corresponding to the signal from one or more of the second pixel of the virtual converting photoelectrically, and.

  In the imaging device according to a twentieth aspect of the present invention, in the nineteenth aspect, the detection processing unit receives signals from the one or more second pixels and from the one or more third pixels. A signal, the signal corresponding to the signal from the one or more virtual third pixels obtained by the first corresponding signal acquisition unit, and the virtual obtained by the second corresponding signal acquisition unit And a signal output by a connection of the one or more second pixels and the one or more second pixels based on the signal corresponding to the signal from the one or more second pixels. And a means for obtaining a detection signal indicating a focus adjustment state of the optical system from a phase difference between a signal output by connection of the one or more third pixels and the virtual one or more third pixels. , Which is provided.

  An image pickup apparatus according to a twenty-first aspect of the present invention performs the focus adjustment of the optical system based on a detection signal from the detection processing unit in any of the seventh to ninth and eighteenth to twentieth aspects. It is equipped with an adjustment part.

  According to the present invention, on the premise of having a function as a focus detection element, a plurality of photoelectric conversion units are not provided in one pixel, thereby avoiding a decrease in aperture ratio and a corresponding decrease in sensitivity. Thus, it is possible to provide a solid-state imaging device capable of reducing deterioration in image quality of a captured image and an imaging apparatus using the same.

  Hereinafter, a solid-state imaging device and an imaging device using the same according to the present invention will be described with reference to the drawings.

  [First Embodiment]

  FIG. 1 is a schematic configuration diagram schematically showing a main part of a digital still camera as an imaging apparatus according to the first embodiment of the present invention.

  The camera according to the present embodiment is configured as a black and white camera, and includes an imaging lens 1 as an optical system for forming a subject image, and a monochrome CMOS solid-state imaging device arranged on a predetermined imaging plane of the imaging lens 1. 2, a signal processing unit 3 that performs signal processing (amplification, A / D conversion, etc.) on a signal from the solid-state imaging device 2, a liquid crystal display unit 4 that displays a monitor image, and the like, and records the captured image on a memory card or the like Commands a recording unit 5 for recording on a medium, a lens driving unit 6 as an adjusting unit that drives a part of the lenses constituting the imaging lens 1 and adjusts the focus of the imaging lens 1, and an aperture that constitutes the imaging lens 1 An aperture drive unit 7 for setting the aperture value, an operation unit 8 such as a shutter button, and a control unit 9 are provided. Although not shown, the imaging lens 1 includes a plurality of lenses and a diaphragm.

  The control unit 9 is configured using a CPU, a memory, and the like, and controls driving of the solid-state imaging device 2 in response to an operation signal from the operation unit 8, controls recording of the recording unit 5, An automatic exposure is realized by controlling the aperture driving unit 7 based on a signal from a photometric unit (not shown). The control unit 9 detects a focus adjustment state of the imaging lens 1 based on a signal obtained from the solid-state imaging device 2 via the signal processing unit 3 (function (focus detection processing as a focus detection processing unit 10)). )), And the lens driving unit 6 is controlled according to the detection result to realize automatic focus adjustment. This automatic focus adjustment will be described in detail later with reference to FIG.

  FIG. 2 is a schematic plan view showing the solid-state imaging device 2 in FIG. In the present embodiment, as shown in FIG. 2, the imaging region 11 of the solid-state imaging device 2 includes two focus detection regions 12 and 13 having a cross shape disposed in the center and two regions disposed on both sides. Focus detection areas 14 and 15 and two focus detection areas 16 and 17 arranged above and below are provided. As shown in FIG. 2, an X axis and a Y axis that are orthogonal to each other are defined. The direction of the arrow in the X-axis direction is called the + X direction or + X side, and the opposite direction is called the -X direction or -X side, and the same applies to the Y-axis direction. A plane parallel to the XY plane coincides with the imaging surface (light receiving surface) of the solid-state imaging device 2. The arrangement in the X-axis direction is a row and the arrangement in the Y-axis direction is a column. These points are the same for the drawings described later.

  FIG. 3 is a schematic enlarged view in which the vicinity of the intersection of the focus detection areas 12 and 13 in FIG. 2 is enlarged, and schematically shows the pixel arrangement. For convenience of explanation, column numbers and row numbers are given as shown in FIG. In FIG. 3, the pixel 20 is blank, the pixel 21 is labeled with “L”, and the pixel 22 is labeled with “U”.

  In the present embodiment, as shown in FIG. 3, the focus detection area 12 is arranged between the pixels 21 arranged in zigzags in the two rows of row numbers 7 and 8 and between the pixels 21 in these two rows. And the pixel 20. The focus detection area 13 includes pixels 22 arranged in a zigzag manner in two columns of column numbers 7 and 8 and pixels 20 arranged between the pixels 22 in these two columns. Although not shown in the drawing, the focus detection areas 14 and 15 are composed of a plurality of pixels 22 and a plurality of pixels 20 in two columns, like the focus detection area 13. Similarly to the focus detection area 12, the focus detection areas 16 and 17 are composed of a plurality of pixels 21 and a plurality of pixels 20 in two rows. All the pixels in the area other than the focus detection areas 12 to 17 in the imaging area 11 of the solid-state imaging device 2 are pixels 20.

  FIG. 4 is a schematic enlarged view of eight pixels (six pixels 20 and two pixels 21 (L)) having row numbers 6 to 9 and column numbers 1 and 2 in FIG. In FIG. 4, the microlens 32 of each pixel and the openings 33a and 33b of the light shielding metal layer 33 in each pixel are also schematically shown. FIG. 5 is a schematic cross-sectional view taken along line X1-X2 in FIG.

  As shown in FIGS. 4 and 5, each of the pixels 20 and 21 (L) includes a photodiode 31 as a photoelectric conversion unit, and a microlens 32 formed on-chip on the photodiode 31. A light shielding metal layer 33 as a light shielding part is formed on the substantially focal plane of the microlens 32. The light shielding portion is not limited to the metal layer, and may be composed of a film of another material. In the light shielding metal layer 33, in the pixel 20, a square opening 33 a concentric with the optical axis O of the microlens 32 of the pixel 20 is formed. In addition, the light shielding metal layer 33 has a pixel 21 (L) on the left side of a square concentric with the optical axis O of the microlens 32 of the pixel 21 (L) (a square having the same size as the opening 33a). -X side) A rectangular opening 33b having a half size is formed. The photodiode 31 of the pixel 20 has a size capable of effectively receiving all the light that has passed through the opening 33a. The photodiode 31 of the pixel 21 (L) has the same size as the photodiode 31 of the pixel 20. The difference between the pixel 20 and the pixel 21 (L) is only the position and size of the opening 33a and the opening 33b with respect to the corresponding microlens 32, as described above. Although the opening 33b is preferably half of the opening 33a as in the present embodiment, the present invention is not necessarily limited to this. For example, the opening 33b is about 40% or about 60% on the left side (−X side) of a concentric square (a square having the same size as the opening 33a) with respect to the optical axis O of the micro lens 32 of the pixel 21 (L). It is good also as a rectangular opening of the size.

  In the present embodiment, in the pixel 20, the opening 33 a is formed in the light-shielding metal layer 33 disposed substantially at the focal plane of the microlens 32, so that the photodiode 31 of the pixel 20 emits from the imaging lens 1. A light beam from the first region of the exit pupil (corresponding to a projection image by the microlens 32 of the opening 33a) that is not substantially decentered from the center of the pupil is received and photoelectrically converted. Further, in the pixel 21, the opening 33 b is formed in the light shielding metal layer 33, so that the photodiode 31 of the pixel 21 (L) is substantially one of the first regions of the exit pupil of the imaging lens 1. A light beam from a region of the exit pupil that forms a part (half in this embodiment) and decentered in the + X direction from the center of the exit pupil is selectively received and photoelectrically converted. Become.

  An interlayer insulating film or the like is formed between the light shielding metal layer 33 and the microlens 32 or between the substrate 34 and the light shielding metal layer 33.

  FIG. 6A is a schematic plan view of the pixel 22 (U), and FIG. 6B is a schematic cross-sectional view taken along line Y1-Y2 in FIG. 6A. 6 (a) and 6 (b), elements that are the same as or correspond to those in FIGS. 4 and 5 are given the same reference numerals, and redundant descriptions thereof are omitted.

  The pixel 22 (U) is different from the pixels 20 and 21 (L) in that the light shielding metal layer 33 is concentric with the optical axis O of the microlens 32 of the pixel 22 (U) in the pixel 22 (U). The only difference is that a rectangular opening 33c having a size just half the upper side (+ Y side) of the square (a square having the same size as the opening 33a) is formed. Thus, the photodiode 31 of the pixel 22 (U) is an area of the exit pupil that substantially forms a part of the first area of the exit pupil of the imaging lens 1 (half in the present embodiment). A light beam from the exit pupil region decentered in the −Y direction from the center of the exit pupil is selectively received and subjected to photoelectric conversion.

  Here, the pixels 23 (R) and 24 (D) which are not actually used in the solid-state imaging device 2 of the imaging apparatus according to the present embodiment but are virtually used are shown in FIGS. 7 and 8, respectively. 7 and 8, elements that are the same as or correspond to those in FIGS. 4 and 5 are given the same reference numerals, and redundant descriptions thereof are omitted.

  FIG. 7A is a schematic plan view of the pixel 23 (R), and FIG. 7B is a schematic cross-sectional view taken along line X3-X4 in FIG. 7A. The pixel 23 (R) is different from the pixels 20 and 21 (L) in that the light shielding metal layer 33 is concentric with the optical axis O of the microlens 32 of the pixel 23 (R) in the pixel 23 (R). This is only a point where a rectangular opening 33d having a size just half the right side (+ X side) of the square (a square having the same size as the opening 33a) is formed. Thereby, the photodiode 31 of the pixel 23 (R) is an area of the exit pupil that substantially forms a part of the first area (half in this embodiment) of the exit pupil of the imaging lens 1. A light beam from the exit pupil region decentered in the −X direction from the center of the exit pupil is selectively received and subjected to photoelectric conversion.

  FIG. 8A is a schematic plan view of the pixel 24D, and FIG. 8B is a schematic cross-sectional view taken along line Y3-Y4 in FIG. The pixel 24 (D) is different from the pixels 20 and 22 (U) in the pixel 24 (D), in which the light shielding metal layer 33 is concentric with the optical axis O of the microlens 32 of the pixel 24 (D). This is only the point that a rectangular opening 33e having a size just half the lower side (-Y side) of the square (a square having the same size as the opening 33a) is formed. Thus, the photodiode 31 of the pixel 24 (D) is an area of the exit pupil that substantially forms a part of the first area of the exit pupil of the imaging lens 1 (half in the present embodiment). The light beam from the exit pupil region decentered in the + Y direction from the center of the exit pupil is selectively received and photoelectrically converted.

  FIG. 9 is an electric circuit diagram showing a schematic configuration of the solid-state imaging device 2 in FIG. In FIG. 9, the pixels 20, 21 (L), and 22 (U) are denoted by reference numeral 100 without distinguishing between them. All of these pixels have the same circuit configuration. That is, as shown in FIG. 9, in addition to the photodiode 31, the pixel 100 includes an amplification MOSFET (Metal Oxide Silicon Field Effect Transistor) 35 that generates an amplification signal based on a signal generated by the photodiode 31, and an amplification A reset switch 36 that resets the input of the MOSFET 35 to a predetermined voltage, a selection switch 39 that controls conduction between the source electrode of the amplification MOSFET 35 and the vertical output line 38, and a photodiode 31 and a gate electrode of the amplification MOSFET 35. And a transfer switch 40 for controlling conduction between the two. The circuit configuration of the pixel 100 is a general circuit configuration of a unit pixel of a CMOS solid-state imaging device.

  In FIG. 9, only the pixels of 2 rows × 2 columns are representatively shown, but the number of pixels of the solid-state imaging device 2 is not particularly limited. Actually, for example, tens to thousands of pixels are arranged in each row and each column, and resolution is increased by increasing the number of pixels.

  As shown in FIG. 9, the solid-state imaging device 2 includes, in addition to the pixel 100, a vertical scanning circuit 41 that controls on / off of the amplification MOSFET 35, the transfer switch 40, and the reset switch 36 of each pixel 100, and each pixel 100. A constant current source 42 for reading a signal from each pixel, a vertical output line 38 for transmitting a signal read from each pixel 100, a signal storage unit 43 for storing a signal read from each pixel 100, and a signal A horizontal scanning circuit 44 that controls reading of the signal accumulated in the accumulation unit 43, a transfer gate 44a for accumulating the dark signal (noise signal) of each pixel 100 in the signal accumulation unit 11, and a bright signal (noise signal is generated). A transfer gate 44b for storing the superimposed optical response signal) in the signal storage unit 11.

  Control signals φRES (n), φSEL (n), φTX (n) are applied to the gate electrodes of the reset switch 36, the selection switch 39, and the transfer switch 40 from the vertical scanning circuit 41 under the control of the control unit 9 in FIG. ) Is applied. Here, n is a positive integer indicating an arbitrary row. Further, a control signal φH (m) is applied to the signal storage unit 43 from the horizontal scanning circuit 42 under the control of the control unit 9 in FIG. Here, m is a positive integer indicating an arbitrary column. The signal storage unit 43 sequentially outputs the bright signal and the dark signal of each column serially for each column in the horizontal scanning period by the control signal φH (m), but outputs the dark signal and the bright signal in parallel. It is like that. Control signals φTS and φTN are respectively applied to the gate electrodes of the transfer gates 44a and 44b from the control unit 9 in FIG.

  Next, the operation of the solid-state imaging device 2 will be described with reference to FIG. FIG. 10 is a timing chart showing the operation of the solid-state imaging device 2.

  When a certain row (hereinafter referred to as the nth row) is selected by the vertical scanning circuit 41, first, the reset signal φRES (n) becomes low, and the reset switch 36 is turned off.

  Next, when the selection signal φSEL (n) becomes high and the selection switch 39 is turned on, the source of the amplifying MOSFET 35 is brought into conduction with the vertical output line 38, and the source is selected by the selected pixel 100 and the constant current source 42. A follower circuit is formed.

  Subsequently, φTN becomes high, and a dark signal (noise signal) corresponding to the reset state of the pixel 100 is read out to the signal storage unit 43 via the transfer gate 44b. Thereafter, the transfer switch 40 is turned on for a certain period by the transfer pulse φTX (n), and the optical signal generated in the photoelectric conversion element 1 is transferred to the gate of the amplification MOSFET 2.

  Subsequently, φTS goes high, and a bright signal corresponding to the optical signal is read out to the signal storage unit 43 via the transfer gate 44a.

  Thereafter, the horizontal scanning period for the nth row is set. In this horizontal scanning period, the horizontal scanning circuit 44 supplies the control signal φH (m) to the signal storage unit 43, so that the signal storage unit 43 sequentially outputs the bright signal and the dark signal of each column serially for each column. . The signal processing circuit 3 in FIG. 1 amplifies these signals, further subtracts the dark signal from the bright signal for each signal from each pixel, and converts this pixel signal to A / D conversion. In this way, by executing the difference between the correlated bright signal and dark signal, a good optical response output with less noise can be obtained.

  By sequentially performing the above operation for all rows, the pixel signals of all the pixels 100 of the solid-state imaging device 2 (that is, the pixel signals of all the pixels 20, 21 (L), 22 (U)) are converted into digital signals. As obtained from the signal processing unit 3.

  Next, the automatic focus adjustment process executed by the control unit 9 will be described with reference to FIG.

  For example, when the shutter button of the operation unit 8 is half-pressed, the control unit 9 starts an automatic focus adjustment process. First, the control unit 9 sends a control signal to the solid-state imaging device 2 to perform the operation described with reference to FIG. The pixel signal of all the pixels 20, 21 (L), 22 (U) is obtained from the signal processing unit 3 and taken into a memory (not shown) included in the control unit 9 (see FIG. 2). Step S1).

  Next, the control unit 9 determines that the currently set focus adjustment mode is a mode in which focus adjustment is performed only based on, for example, the focus detection area 12 shown in FIGS. 2 and 3 (hereinafter referred to as “focus detection area 12 mode”). .)), In step S2, the pixel 21 based on the signal of each pixel 21 (L) in the focus detection area 12 and the signal of the pixel 20 in the vicinity thereof among the pixel signals captured in step S1. A signal corresponding to the signal from the virtual pixel 23 (R) shown in FIG. 7 paired with (L) is calculated.

  Specifically, for example, the pixel signal (pixel value) of the pixel 20 in the eighth row and first column (row number 8 and column number 1) in FIG. ) Or the average of the pixel signal of the pixel 20 of the eighth row and first column and the pixel signal of the pixel 20 of the sixth row and first column, and the pixel 21 ( The pixel signal obtained by subtracting the pixel signal of (L) is acquired as the pixel signal corresponding to the pixel signal of the pixel 21 (L) in the seventh row and first column. Further, the pixel signal of the pixel 20 of the eighth row and the second column subtracted from the pixel signal of the pixel 20 of the seventh row and the second column, or the pixel signal of the pixel 20 of the seventh row and the second column The average of the pixel signal of the pixel 20 of the 9th row and the 2nd column and the pixel signal of the pixel 21 (L) of the 8th row and 2nd column is subtracted from the average of the pixel signal of the pixel 21 (L) of the 8th row and 2nd column. Obtained as a pixel signal corresponding to the pixel signal. Similarly, a signal corresponding to the pixel signal of each of the other pixels 21 (L) in the focus detection area 12 is acquired.

  These are the amount of light from the first region (corresponding to the pixel signal of the pixel 20) that is not substantially decentered from the center of the exit pupil of the imaging lens 1, and the amount of light from the half region of the first region (pixel 21 (L) corresponding to the pixel signal) is subtracted, the light amount from the opposite half region of the first region (the light amount not actually detected by the pixel and the virtual pixel 23 ( This is based on the new knowledge obtained by the present inventor that the pixel signal of R) is known.

  In addition, the currently set focus adjustment mode is a mode in which focus adjustment is performed based on, for example, all the focus detection areas 12 to 17 shown in FIGS. 2 and 3 (hereinafter referred to as “all focus detection area mode”). If there is, in step S2, the signal corresponding to the pixel signal of each pixel 21 (L) in the focus detection region 12 is acquired as described above for the focus detection region 12, and also for each focus detection region 13-17. Similarly, a signal corresponding to the pixel signal of each pixel 22 (L) or each pixel 22 (U) in the focus detection region 12 is acquired.

  For example, for the focus detection area 13, the pixel 22 (U) is selected based on the signal of each pixel 22 (U) in the focus detection area 13 and the signal of the pixel 20 in the vicinity of the pixel signal captured in step S 1. A signal corresponding to the signal from the pixel 24 (D) shown in FIG. Specifically, for example, a signal obtained by subtracting the pixel signal of the pixel 22 (U) in the first row and the seventh column from the pixel signal of the pixel 20 in the first row and the eighth column in FIG. A value obtained by subtracting the pixel signal of the pixel 22 (U) in the first row and the seventh column from the average of the pixel signal of the pixel 20 in the sixth column and the pixel signal of the pixel 20 in the first row and the eighth column is the first row and the second row. Obtained as pixel signals corresponding to the pixel signals of the seven columns of pixels 22 (U). Also, the pixel signal of the pixel 20 of the second row and eighth column subtracted from the pixel signal of the pixel 22 (U) of the second row and eighth column, or the pixel signal of the pixel 20 of the second row and seventh column A value obtained by subtracting the pixel signal of the pixel 22 (U) in the second row and eighth column from the average of the pixel signal of the pixel 20 in the second row and ninth column is the pixel 22 (U) in the second row and eighth column. Obtained as a pixel signal corresponding to the pixel signal. Similarly, a signal corresponding to the pixel signal of each of the other pixels 21 (L) in the focus detection area 13 is acquired.

  Next, in step S3, when the currently set focus adjustment mode is the focus detection area 12 mode, the control unit 9 determines that all the pixels 21 in the focus detection area 12 among the pixel signals captured in step S1. The signal output by the connection of (L) (that is, the signal formed as a whole when the pixel signals of all the pixels 21 (L) in the focus detection region 12 are arranged in the column order) and the virtual FIG. When the signals obtained in step S2 are arranged in the order of columns corresponding to all the pixels 21 (L) in the focus detection region 12, they are output as a whole. The defocus amount in the focus detection area 12 is calculated as a detection signal indicating the focus adjustment state of the imaging lens 1 by calculating the phase difference with the signal formed. As the calculation method itself, a calculation method known by a pupil division phase difference method may be used.

  When the currently set focus adjustment mode is the all-focus detection area mode, the control unit 9 calculates the defocus amount with respect to the focus detection area 12 as described above, and also for each of the focus detection areas 13 to 17. Similarly, a defocus amount is calculated for the focus detection area.

  Steps S <b> 2 and S <b> 3 described above correspond to the function as the focus detection processing unit 10 in the control unit 9.

  After step S3, in step S4, if the currently set focus detection mode is the focus detection region 12 mode, the control unit 9 performs the defocusing based on the defocus amount related to the focus detection region 12 obtained in step S3. A focus adjustment command signal is output to the lens driving unit 6 so that the focus amount becomes zero. As a result, the lens driving unit 6 adjusts the focus state of the imaging lens 1 and focuses in the focus detection region 12.

  When the currently set focus detection mode is the all-focus detection area mode, the lens driving unit is set so that the adjusted focus adjustment state determined based on the defocus amount of each focus detection area obtained in step S3. 6 outputs a focus adjustment command signal. As a result, the lens driving unit 6 adjusts the focus state of the imaging lens 1 to be in the determined focus adjustment state.

  Then, when the shutter button is fully pressed, the operation described with reference to FIG. 10 is performed by the solid-state imaging device 2 under the control of the control unit 9, and all the pixels 20, 21 (L), 22 (U) pixel signals are obtained, and the signal control unit 3 performs interpolation processing on the positions of the pixels 21 (L) and 22 (U), and the pixel signal of the pixel 20 and the pixel 21 (L). , 22 (U), an image (captured image) composed of pixel signals obtained by interpolation processing is written by the recording unit 5 on a recording medium.

  In addition to the plurality of imaging pixels, the solid-state imaging device disclosed in Patent Document 1 described above includes a plurality of first focus detection pixels (pixels to which “S1” is attached in Patent Document 1), and a plurality of pixels. Second focus detection pixels (pixels labeled with “S2” in Patent Document 1), and only the first and second focus detection pixels are used for focus detection, and a plurality of imaging is performed. No pixel is used. If the solid-state imaging device 2 according to the present embodiment is modified in accordance with this prior art, a solid-state imaging device according to the comparative example shown in FIG. 12 is obtained.

  FIG. 12 is a partially enlarged plan view showing a solid-state image sensor according to a comparative example compared with the solid-state image sensor 2 according to the present embodiment, and corresponds to FIG. 12, elements that are the same as or correspond to those in FIGS. 3 to 8 are given the same reference numerals, and redundant descriptions thereof are omitted.

  As can be seen by comparing FIG. 12 with FIG. 3, in FIG. 12, instead of the pixel 20, the pixel 23 (R) shown in FIG. The pixel 24 (D) shown in FIG. That is, in FIG. 12, the pixels 23 (R) are actually arranged in a zigzag manner in the two rows with row numbers 9 and 10, and the pixels 24 (D) are actually arranged in a zigzag manner in the two columns with column numbers 9 and 10. Has been.

  When the solid-state imaging device shown in FIG. 12 is used, step S2 in FIG. 11 is not performed. In step S3, for example, when the currently set focus detection mode is the focus detection region 12 mode, the control unit 9 Of the pixel signals captured in S1, a signal output by the connection of all the pixels 21 (L) in the focus detection area 12 (that is, the pixel signals of all the pixels 21 (L) in the focus detection area 12 are arranged in a column. Signals formed as a whole when they are arranged in sequence) and signals output by the connection of all the pixels 23 (R) in the focus detection area 12 among the pixel signals captured in step S1 (that is, the focus detection area) 12 is calculated by calculating the phase difference between the pixel signals of all the pixels 23 (R) in the pixel 12 and the signals formed as a whole when the pixel signals are arranged in the column order. The definitive defocus amount is calculated as a detection signal indicating a focusing state of the imaging lens 1.

  In the solid-state imaging device according to the comparative example shown in FIG. 12, pixels 21 (L), 22 (U), 23 (R), and 24 (D) that are used only for focus detection and cannot be used during image capturing. Since there are many numbers, degradation of the image quality of the captured image is large.

  On the other hand, in the present embodiment, as shown in FIG. 3, the number of pixels 21 (L) and 22 (U) that are used only for focus detection and cannot be used at the time of image capturing are as shown in FIG. Therefore, the degradation of the image quality of the captured image can be greatly reduced.

  In this embodiment, photodiodes 31 are provided on a one-to-one basis with respect to a pixel, and a plurality of photodiodes are not provided for each pixel. Therefore, a plurality of transfer units are provided in one pixel. There is no need. Therefore, according to the present embodiment, unlike the case of the solid-state imaging device disclosed in Patent Document 2, it is possible to avoid a decrease in aperture ratio and a decrease in sensitivity associated therewith.

  Further, in the present embodiment, the focus detection areas 12, 16, and 17 are configured with pixels 20 and 21 (L) that can divide the exit pupil of the imaging lens 1 into left and right. Therefore, by using the focus detection areas 12, 16, and 17, for example, it becomes easy to detect the focus when capturing an image of a vertical stripe pattern. The focus detection regions 13 to 15 are configured by pixels 20 and 22 (U) that can divide the exit pupil of the imaging lens 1 into upper and lower portions. Therefore, by using the focus detection regions 13 to 15, for example, it becomes easier to detect the focus when capturing a horizontal stripe pattern image.

  Furthermore, in this embodiment, the pixels 21 (L) and 22 (U) are arranged in a zigzag shape. Therefore, compared with the case where the pixels 21 (L) and 22 (U) are arranged in a straight line, the influence on the picked-up image quality is reduced, which is preferable. However, the present invention is not limited to such an arrangement, and the pixels 21 (L) and 22 (U) may be arranged in a straight line, for example.

  [Second Embodiment]

  FIG. 13 is a partially enlarged plan view showing a solid-state imaging device used in a digital still camera as an imaging apparatus according to the second embodiment of the present invention, and corresponds to FIG. 13, elements that are the same as or correspond to those in FIGS. 3 to 7 are given the same reference numerals, and redundant descriptions thereof are omitted.

  The camera according to the present embodiment differs from the camera according to the first embodiment only in the configuration of the solid-state imaging device and the processing contents of steps S2 and S3 in FIG.

  The solid-state imaging device shown in FIG. 13 is different from the solid-state imaging device 2 shown in FIG. 3 or the like used in the first embodiment except that the solid-state imaging device shown in FIG. The only difference is that each pixel 21 (L) in the column of the eighth row is replaced with a pixel 23 (R) shown in FIG.

  In the present embodiment, in step S2 in FIG. 11, when the currently set focus adjustment mode is the focus detection region 12 mode, the control unit 9 performs the focus detection region out of the pixel signals captured in step S1. 12 corresponds to a signal from a virtual pixel 23 (R) shown in FIG. 7 that forms a pair with the pixel 21 (L), based on the signal of each pixel 21 (L) in FIG. Calculate the signal. Further, the control unit 9 determines the pixel 23 (R) and the pixel 23 (R) based on the signal of each pixel 23 (R) in the focus detection area 12 and the signal of the pixel 20 in the vicinity thereof among the pixel signals captured in step S1. A signal corresponding to the signal from the pixel 21 (L) as shown in FIG. 3 and FIG. 4 forming a pair is calculated.

  Specifically, for example, the pixel signal (pixel value) of the pixel 20 in the eighth row and first column (row number 8 and column number 1) in FIG. ) Or the average of the pixel signal of the pixel 20 of the eighth row and first column and the pixel signal of the pixel 20 of the sixth row and first column, and the pixel 21 ( The pixel signal obtained by subtracting the pixel signal of (L) is acquired as the pixel signal corresponding to the pixel signal of the pixel 21 (L) in the seventh row and first column. Similarly, a signal corresponding to the pixel signal of each of the other pixels 21 (L) in the focus detection area 12 is acquired. Further, for example, the pixel signal of the pixel 20 of the eighth row and the second column from the pixel signal of the pixel 20 of the seventh row and the second column, or the pixel of the pixel 20 of the seventh row and the second column The pixel 23 (R) in the eighth row and second column is obtained by subtracting the pixel signal of the pixel 23 (R) in the eighth row and second column from the average of the signal and the pixel signal of the pixel 20 in the ninth row and second column. ) Is obtained as a pixel signal corresponding to the pixel signal. Similarly, a signal corresponding to the pixel signal of each of the other pixels 23 (R) in the focus detection area 12 is acquired.

  In the present embodiment, in step S3 in FIG. 11, when the currently set focus adjustment mode is the focus detection area 12 mode, the control unit 9 performs the focus detection area in the image signal captured in step S1. 12 (L) and a signal output by the connection of the virtual pixel 21 (L) as shown in FIGS. 4 and 5 (that is, all the pixels 21 (L) in the focus detection region 12). And the signal obtained in correspondence with the pixel 23 (R) in step S2 as a whole when they are arranged in the order of columns) and the focus detection region 12 in the image signal captured in step S1. 7 (R) and a signal output by the connection of the virtual pixels 23 (R) as shown in FIG. 7 (that is, the pixel signals of all the pixels 23 (R) in the focus detection area 12 and The By calculating the phase difference from the signals obtained as a whole when the signals obtained corresponding to the pixels 21 (L) are arranged in the column order in step S2, the defocus amount in the focus detection area 12 is calculated. Then, it is calculated as a detection signal indicating the focus adjustment state of the imaging lens 1. As the calculation method itself, a calculation method known by a pupil division phase difference method may be used.

  According to the present embodiment, the pixels 21 (L) and 23 (R) are arranged in the focus detection area 12 as in the comparative example shown in FIG. 12 described above, but the pixels 21 (L) are used for focus detection. , 23 (R), the number of pixels 21 (L), 23 (R), and 22 (U) that are used only for focus detection and cannot be used when capturing an image is As in the case of the first embodiment, half of the case of FIG. 12 is required, so that the deterioration of the image quality of the captured image can be greatly reduced.

  As described above, this embodiment can provide the same advantages as those of the first embodiment.

  In the present invention, as in the present embodiment, an arbitrary number of pixels 21 (L) in the focus detection region 12 in FIG. 3 are replaced with pixels 23 (R) shown in FIG. Also good. For example, only the pixel 21 (L) in the seventh row and the third column in the focus detection area 12 in FIG. 3 may be replaced with the pixel 23 (R) shown in FIG.

  Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.

  For example, in each of the above-described embodiments, as described above, the photodiode 31 of the pixel used only for focus detection has the same size as the photodiode of the pixel 20 used for imaging, and only the focus detection is performed by the light shielding by the light shielding metal layer 33. The area of the exit pupil of the photographic lens 1 that is received by the photodiode 31 of the pixel used in FIG. However, the size of the photodiode 31 of the pixel used only for focus detection may be halved without using such light shielding.

  An example of this is shown in FIG. FIG. 14 shows a modification of the first and second embodiments, is a schematic cross-sectional view showing the pixels 20 and 21 (L), and corresponds to FIG. 4, elements that are the same as or correspond to those in FIG. 5 are given the same reference numerals, and redundant descriptions thereof are omitted. In FIG. 14, the light shielding metal layer 33 provided in FIG. 5 is removed, and the size of the photodiode 31 of the pixel 21 (L) is halved. In this case, it is preferable to set so that the photodiode 31 is positioned on the focal plane of the microlens 32. Note that, as shown in FIG. 14, even when the size of the photodiode 31 of the pixel 21 (L) is halved, a light shielding film may be appropriately formed to shield unnecessary light as necessary. Good.

  In each of the above-described embodiments, a CMOS solid-state image sensor is used as the solid-state image sensor. However, a CCD type or other image sensor may be used.

  Further, in each of the above embodiments, at the time of focus detection, signals of all pixels are output from the solid-state imaging device in step S1 in FIG. 11, but the pixels 21 (L), 22 (U), and 23 (R ) And the surrounding pixels 20 may be output to increase the speed.

  Furthermore, in each of the embodiments described above, the exit pupil of the imaging lens 1 is divided into left and right and top and bottom. However, the opening shape of the light-shielding portion may be changed to divide in any direction such as diagonally. There may be pixel groups divided in different directions.

  In each of the above embodiments, a monochrome solid-state image sensor is used. However, the present invention can also be applied to a color solid-state image sensor. An example is shown in FIG.

  FIG. 15 shows an example in which the monochrome solid-state image pickup device 2 of the first embodiment is modified to a color solid-state image pickup device. In this solid-state imaging device, no color filter is formed on the pixels 21 (L) and 22 (U), while one of R, G, and B color filters 50 is formed on the pixel 20.

  In addition, as a specific example of the arrangement of the pixels 20 and the pixels 21 (L) of each color in the case of a color solid-state imaging device, for example, when the focus detection region is only one of the focus detection regions 12, for example, Patent Literature 2, 6, 7, and 8, the R, G, and B pixels are respectively R, G, and B pixels 20, and the S1 pixel is a pixel 21 (L). And the S2 pixel may be the G pixel 20. Of course, the present invention is not limited to such an arrangement.

  As described above, unless a color filter is arranged in the other pixel 21 (L) or the like, the signal intensity from the pixel does not decrease by the amount of the color filter, so the SN ratio of the pixel signal does not decrease. This is preferable because the accuracy of focus detection increases.

  However, when the color filter 50 is formed only in the pixel 20 and the color filter is not disposed in the other pixel 21 (L) or the like, the transmittance of the color filter 50 is considered in step S2 in FIG. Adjust both levels. That is, the pixel signal of the pixel 20 used in the description of step S2 in FIG. 11 is used by replacing it with a signal adjusted in level by dividing by the transmittance of the color filter of the pixel 20.

  Further, in each of the above embodiments, the number and position of the focus detection areas are as shown in FIG. 2, but are not particularly limited. For example, one focus detection area may be provided.

  Furthermore, each of the above embodiments is an example in which the present invention is applied to a digital still camera, but the present invention can also be applied to other imaging devices such as a video camera.

It is a schematic block diagram which shows typically the principal part of the digital still camera by the 1st Embodiment of this invention. It is a schematic plan view which shows the solid-state image sensor in FIG. FIG. 3 is a schematic enlarged view in which the vicinity of an intersection of two central focus detection areas in FIG. 2 is enlarged. FIG. 4 is a schematic enlarged view of some pixels in FIG. 3. It is a schematic sectional drawing in alignment with the X1-X2 line | wire in FIG. It is a figure which shows the predetermined pixel in FIG. It is a figure which shows the other predetermined pixel in FIG. It is a figure which shows the other predetermined pixel in FIG. It is an electric circuit diagram which shows schematic structure of the solid-state image sensor in FIG. It is a timing chart which shows operation | movement of the solid-state image sensor in FIG. It is a schematic flowchart which shows the automatic focus adjustment process which the control part in FIG. 1 performs. It is a partially expanded plan view which shows the solid-state image sensor by a comparative example. FIG. 6 is a partially enlarged plan view showing a solid-state imaging device used in a digital still camera according to a second embodiment of the present invention. It is a schematic sectional drawing which shows the predetermined pixel in the modification of the said 1st and 2nd embodiment. It is a schematic sectional drawing which shows the modification of the 1st Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shooting lens 2 Solid-state image sensor 10 Focus detection process part 11-17 Focus detection area 20, 21, 22, 23, 24 Pixel 31 Photodiode 32 Micro lens 33 Light-shielding metal layer 33a, 33b, 33c, 33d, 33e Aperture

Claims (21)

A solid-state imaging device that photoelectrically converts a subject image formed by an optical system,
A plurality of first pixels that receive and photoelectrically convert a light beam from the first region of the exit pupil that is not substantially decentered from the center of the exit pupil of the optical system; A plurality of second regions that selectively receive and photoelectrically convert a light beam from a second region of the exit pupil that is part of the second region of the exit pupil and that is decentered in a predetermined direction from the center of the exit pupil. 2 pixels,
The plurality of first pixels are used to obtain an electrical signal indicating an image corresponding to the subject image;
Of the plurality of first pixels, the first pixel in the vicinity of the plurality of second pixels and the plurality of second pixels obtain an electric signal for detecting a focus adjustment state of the optical system. A solid-state image pickup device used for the purpose.   In one focus detection region including the first pixel and the plurality of second pixels in the vicinity of the plurality of second pixels among the plurality of first pixels, the first pixel is substantially included in the first focus detection region. Selectively receiving a light beam from the third region of the exit pupil, which is a third region of the exit pupil that forms part of the region and is decentered from the center of the exit pupil in a direction opposite to the predetermined direction. 2. The solid-state imaging device according to claim 1, wherein a pixel that performs photoelectric conversion is not included.   3. The solid-state imaging device according to claim 1, wherein the second region is a substantially half region of the first region. 4.   The second pixel has a photoelectric conversion unit having the same size as the first pixel, and the photoelectric conversion unit of the second pixel is partially shielded by the light shielding unit, whereby the second pixel 4. The solid-state imaging device according to claim 1, wherein the solid-state imaging device selectively receives a light beam from the second region of the exit pupil. 5.   The second pixel has a photoelectric conversion unit smaller than the first pixel to selectively receive a light beam from the second region of the exit pupil. The solid-state imaging device according to any one of the above.   6. The solid-state imaging device according to claim 1, wherein a color filter is formed on the plurality of first pixels, and a color filter is not formed on the plurality of second pixels. .   The solid-state imaging device according to claim 1, a signal from a first pixel in the vicinity of the plurality of second pixels of the plurality of first pixels, and the plurality of second pixels An imaging apparatus comprising: a detection processing unit that outputs a detection signal indicating a focus adjustment state of the optical system based on a signal from a pixel.   The detection processing unit is configured to output the plurality of pixels based on a signal from a first pixel in the vicinity of the plurality of second pixels and a signal from the plurality of second pixels among the plurality of first pixels. A plurality of virtual third pixels that are paired with the second pixel of the first pixel, the third region of the exit pupil substantially forming part of the first region, and the center of the exit pupil To obtain a signal corresponding to signals from a plurality of virtual third pixels that selectively receive a light beam from the third region of the exit pupil that is decentered in a direction opposite to the predetermined direction and photoelectrically convert it. The imaging apparatus according to claim 7, further comprising a corresponding signal acquisition unit.   The detection processing unit, based on the signals from the plurality of second pixels and the signals corresponding to the signals from the virtual plurality of third pixels obtained by the corresponding signal acquisition unit, Means for obtaining a detection signal indicating a focus adjustment state of the optical system from a phase difference between a signal output by connection of a plurality of second pixels and a signal output by connection of the virtual plurality of third pixels The imaging apparatus according to claim 8, further comprising: A solid-state imaging device that photoelectrically converts a subject image formed by an optical system,
A plurality of first pixels that receive and photoelectrically convert a light beam from the first region of the exit pupil that is not substantially decentered from the center of the exit pupil of the optical system; One or more light beams from the second region of the exit pupil, which are part of the second region of the exit pupil and decentered in a predetermined direction from the center of the exit pupil, are selectively received and photoelectrically converted. The second pixel and the third region of the exit pupil that substantially forms part of the first region, the exit being decentered in a direction opposite to the predetermined direction from the center of the exit pupil One or more third pixels that selectively receive and photoelectrically convert a light beam from the third region of the pupil, and
The plurality of first pixels are used to obtain an electrical signal indicating an image corresponding to the subject image;
A first pixel in the vicinity of the one or more second pixels of the plurality of first pixels and a vicinity of the one or more third pixels, the one or more second pixels, and The solid-state imaging device, wherein the one or more third pixels are used to obtain an electrical signal for detecting a focus adjustment state of the optical system.   The solid-state image pickup device according to claim 10, wherein the second region is a substantially half region of the first region.   The solid-state imaging device according to claim 10 or 11, wherein the third region is a region that is substantially half of the first region.   The second pixel has a photoelectric conversion unit having the same size as the first pixel, and the photoelectric conversion unit of the second pixel is partially shielded by the light shielding unit, whereby the second pixel The solid-state imaging device according to claim 10, wherein the solid-state imaging device selectively receives a light beam from the second region of the exit pupil.   The third pixel has a photoelectric conversion unit having the same size as the first pixel, and the photoelectric conversion unit of the third pixel is partially shielded by the light shielding unit, whereby the third pixel The solid-state imaging device according to claim 10, which selectively receives a light beam from the third region of the exit pupil.   The second pixel has a photoelectric conversion unit smaller than the first pixel, and selectively receives a light beam from the second region of the exit pupil. The solid-state imaging device according to any one of the above.   The third pixel has a photoelectric conversion unit smaller than the first pixel, and selectively receives a light beam from the third region of the exit pupil. And 15. The solid-state imaging device according to any one of 15.   The color filter is formed in the plurality of first pixels, and the color filter is not formed in the one or more second pixels and the one or more third pixels. The solid-state imaging device according to any one of 10 to 16.   18. The solid-state imaging device according to claim 10, and the vicinity of the one or more second pixels and the vicinity of the one or more third pixels of the plurality of first pixels. A detection signal indicating a focus adjustment state of the optical system based on a signal from the first pixel, a signal from the one or more second pixels, and a signal from the one or more third pixels; An image pickup apparatus comprising: a detection processing unit for outputting;   The detection processing unit is based on a signal from a first pixel in the vicinity of the one or more second pixels of the plurality of first pixels and a signal from the one or more second pixels. And one or more virtual third pixels paired with the one or more second pixels, selectively receiving light from the third region of the exit pupil and performing photoelectric conversion A first corresponding signal acquisition unit that obtains a signal corresponding to a signal from one or more virtual third pixels, and the vicinity of the one or more third pixels of the plurality of first pixels One or more virtual second pixels paired with the one or more third pixels based on a signal from the first pixel and a signal from the one or more third pixels. Then, signals from one or more virtual second pixels that selectively receive and photoelectrically convert a light beam from the second region of the exit pupil. Response and second corresponding signal acquisition unit to obtain a signal to imaging apparatus according to claim 18, wherein the containing.   The detection processing unit includes a signal from the one or more second pixels, a signal from the one or more third pixels, and the virtual 1 obtained by the first corresponding signal acquisition unit. The signal corresponding to the signal from one or more third pixels and the signal corresponding to the signal from the one or more second pixels obtained by the second corresponding signal acquisition unit. Based on the signal output by the connection of the one or more second pixels and the virtual one or more second pixels, and the one or more third pixels and the virtual one or more second The imaging apparatus according to claim 19, further comprising means for obtaining a detection signal indicating a focus adjustment state of the optical system from a phase difference with a signal output by a connection of three pixels.   21. The imaging apparatus according to claim 7, further comprising an adjustment unit that performs focus adjustment of the optical system based on a detection signal from the detection processing unit.

Images