JP2017183992A - Image pickup device, focus detection apparatus, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly perform AF processing without regard to the color of a subject, in an imaging apparatus comprising a single-plate-type multilayered image pickup device.SOLUTION: A single-plate-type multilayered image pickup device 32 is obtained by laminating and arranging plural photoelectric conversion layers 62B, 62G, and 62R in this order on a silicon substrate 75. Pixels for focus detection PB, PG, and PR are arranged in the respective photoelectric conversion layers. The pixel signal mean values of the photoelectric conversion layers 62B, 62G, and 62R are compared with each other and the pixel for focus detection of a photoelectric conversion layer which outputs the largest mean value is used to execute the AF processing.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an image pickup apparatus having a focus detection function, and more particularly to focus detection using an image pickup element including a stacked photoelectric conversion layer.

  In a digital camera, a configuration is known in which focus detection pixels are provided in part of a pixel array of an image sensor for imaging and focus detection is performed using a phase difference method. A pair of focus detection pixels forms a pair of split images by dividing the light beam passing through the photographing lens by a pair of focus detection pixels, detects a pattern shift of the split images, and calculates a defocus amount. It is possible to arrange focus detection pixels for an image sensor having a photoelectric conversion unit made of an organic photoelectric conversion layer instead of a normal photodiode, and between the organic photoelectric conversion layer and the microlens. There is known an imaging device in which a light shielding film is formed at a symmetrical position (see Patent Document 1).

  On the other hand, a monochromatic image sensor (first image sensor) that performs photoelectric conversion using a silicon photodiode and an image sensor (second image sensor) including an organic photoelectric conversion film thereon are stacked on the same semiconductor substrate. A method of performing focus detection by a phase difference method using a solid-state imaging device is also known (see Patent Document 2).

  In the second imaging element, an organic photoelectric conversion film that photoelectrically converts light corresponding to Cy, Ye, Mg, and G is two-dimensionally arranged, and light that passes through the photoelectric conversion film is arranged below. 1 is incident on the image sensor. When light corresponding to R, G, and B, which are complementary colors of Cy, Mg, and Ye, enter the monochrome image sensor, the first image sensor is used for a captured image, and the second image sensor above the first image sensor is used for focus detection. Can be used.

JP 2014-67948 A JP 2013-145292 A

  In the case of an image sensor in which one or more photoelectric conversion layers are stacked, the imaging position differs depending on the subject due to the chromatic aberration of the photographing lens due to the influence of the spectral reflectance of the subject and the spectral characteristics of the illumination light. An error occurs.

  Therefore, it is required to accurately detect the focus using an image sensor provided with a photoelectric conversion layer regardless of the color of the subject, illumination light, and the like.

  The imaging device of the present invention includes an imaging device in which a plurality of photoelectric conversion layers that photoelectrically convert light in different wavelength ranges are stacked, and a focus detection pixel signal output from a focus detection pixel provided in each photoelectric conversion layer. And a focus detection unit that executes a focus detection process. Each photoelectric conversion layer selectively absorbs light in a predetermined wavelength region and performs color separation by transmitting light in other wavelength regions. The photoelectric conversion layer can perform focus detection by a phase difference method by providing at least one pair of focus detection pixels provided with a light shielding film at symmetrical positions.

  In the present invention, the focus detection unit selects the focus detection pixel signal or adjusts the focus detection pixel signal so as to suppress the focus detection error based on the difference between the pixel signal levels output from the plurality of photoelectric conversion layers. Here, “select” means selecting at least one focus detection pixel signal, that is, selecting a photoelectric conversion layer provided with focus detection pixels. “Adjustment” indicates that the output level of the focus detection pixel signal of each photoelectric conversion layer is adjusted.

  For example, the focus detection unit can perform focus detection processing using the focus detection pixel of the photoelectric conversion layer that outputs the largest pixel signal among the plurality of photoelectric conversion layers. In addition, the focus detection unit can weight the pixel signals of each photoelectric conversion layer according to the ratio or ratio of the pixel signal levels in the plurality of photoelectric conversion layers.

  About several photoelectric conversion layers, it is good to laminate | stack in order of the photoelectric conversion layer with a long photoelectric conversion wavelength range from the photoelectric conversion layer with a short photoelectric conversion wavelength range along an optical path. For example, a plurality of photoelectric conversion layers, a photoelectric conversion layer that photoelectrically converts light according to B, a photoelectric conversion layer that photoelectrically converts light according to G, a photoelectric conversion layer that photoelectrically converts light according to R, and Can be arranged in this order from the incident side. Furthermore, a photoelectric conversion layer that photoelectrically converts light corresponding to IR can be disposed on the most substrate side.

  In order to support various ranging methods, each photoelectric conversion layer is preferably provided with a focus detection pixel in each of a plurality of divided ranging areas defined according to the ranging points of the imaging area. The focus detection unit can select the focus detection pixel signal or adjust the focus detection pixel signal for the target divided ranging area.

  A program according to another aspect of the present invention outputs an imaging device from a focus detection pixel provided in each photoelectric conversion layer of an imaging element in which a plurality of photoelectric conversion layers that photoelectrically convert light in different wavelength ranges are stacked. The detection of the focus detection pixel signal or the focus detection pixel so as to suppress the focus detection error based on the difference between the means for detecting the level of the focus detection pixel signal and the pixel signal level output from the plurality of photoelectric conversion layers It functions as a means for adjusting the signal.

  According to another aspect of the present invention, a focus detection apparatus includes a focus output from a focus detection pixel provided in each photoelectric conversion layer of an imaging element in which a plurality of photoelectric conversion layers that transmit light in different wavelength ranges are stacked. A focus detection device that performs a focus detection process based on a detection pixel signal, wherein the focus detection pixel signal is controlled so as to suppress a focus detection error based on a difference in pixel signal levels output from a plurality of photoelectric conversion layers. Select or adjust the focus detection pixel signal.

  The focus detection method according to another aspect of the present invention is output from a focus detection pixel provided in each photoelectric conversion layer of an imaging element in which a plurality of photoelectric conversion layers that photoelectrically convert light in different wavelength ranges are stacked. A focus detection method for performing focus detection processing based on a focus detection pixel signal, wherein the focus detection pixel signal is configured to suppress a focus detection error based on differences in pixel signal levels output from a plurality of photoelectric conversion layers. Adjustment or selection of a focus detection pixel signal.

  An imaging device according to another aspect of the present invention includes a plurality of photoelectric conversion layers that are on a substrate and photoelectrically convert light in different wavelength ranges, and a pixel signal readout circuit that reads pixel signals from the plurality of photoelectric conversion layers. A plurality of photoelectric conversion layers are stacked, and each photoelectric conversion layer has a focus detection pixel.

  An imaging device according to another aspect of the present invention photoelectrically converts light in the shortest wavelength region among a plurality of photoelectric conversion layers and an imaging element in which a plurality of photoelectric conversion layers that photoelectrically convert light in different wavelength regions are stacked. A focus detection unit that performs focus detection processing based on focus detection pixel signals output from focus detection pixels provided in photoelectric conversion layers other than the photoelectric conversion layer and photoelectric conversion layers that photoelectrically convert light in the longest wavelength range With. Thereby, it is possible to prevent the focus detection error amount from being remarkably increased even for various subject colors. For example, the focus detection pixel may be provided only in the photoelectric conversion layer that photoelectrically converts light corresponding to G (or light close thereto).

  An imaging device according to another aspect of the present invention includes a plurality of photoelectric conversion layers that are on a substrate and photoelectrically convert light in different wavelength ranges, and a pixel signal readout circuit that reads pixel signals from the plurality of photoelectric conversion layers. A plurality of photoelectric conversion layers are laminated, and the plurality of photoelectric conversion layers are photoelectric conversion layers that photoelectrically convert light in the shortest wavelength region and photoelectric conversion layers other than the photoelectric conversion layer that photoelectrically converts light in the longest wavelength region A photoelectric conversion layer provided with focus detection pixels is provided.

  According to the present invention, in an imaging apparatus including a single-plate multilayer imaging device, AF processing can be appropriately performed regardless of the color of the subject.

It is a block diagram of the digital camera which is 1st Embodiment. It is the figure which showed typically the laminated structure of an image pick-up element. It is the figure which showed the internal structure of the predetermined pixel of an image pick-up element. It is the figure which showed the pixel for focus detection provided in each photoelectric converting layer. It is the figure which showed the division | segmentation ranging area prescribed | regulated to an imaging area. It is a flowchart of the focus detection process performed by a system control circuit. It is the figure which showed chromatic aberration. It is the figure which showed lamination | stacking of the photoelectric converting layer in 2nd Embodiment. It is a flowchart of the focus detection process in 2nd Embodiment. It is a flowchart of the focus detection process in 3rd Embodiment.

  Below, the digital camera which is this embodiment is demonstrated with reference to drawings. FIG. 1 is a block diagram of a digital camera according to the first embodiment.

  The digital camera 10 includes a camera body 30 and an interchangeable lens 20 that is detachable from the camera body 30. The system control circuit 40 including the camera CPU outputs a control signal to the lens control circuit 56, the image processing circuit 34, etc. in accordance with an input operation to a power button, a release button, a mode selection dial (not shown), and the like. A series of camera operation control such as adjustment, shooting control, image processing, recording processing, and playback display processing is performed.

  The system control circuit 40 includes a calculation unit, ROM, RAM, interface circuit, and the like (all not shown), and a camera operation control program is stored in a recording medium (not shown) such as a ROM. The operation switch group 38 includes a power switch, a shooting mode selection switch, a release switch, and the like. A timing generator (not shown) outputs a clock pulse signal having a predetermined frequency to each circuit. The operation timing of each circuit follows the clock pulse signal sent.

  In the photographing mode, light from the subject that has passed through the photographing optical system 22 forms an image on the light receiving surface of the image sensor 32, and a subject image is formed on the image sensor 32. Here, the imaging element 32 is a single-plate CMOS image sensor in which (M × N) pixels are arranged, and is configured as a multilayer imaging element in which a plurality of photoelectric conversion layers are arranged in a stacked manner, as will be described later. ing. The image sensor drive circuit 36 drives the image sensor 32 and reads out pixel signals for one field or one frame from the image sensor 32 at predetermined time intervals. An XY address type image sensor other than CMOS may be used.

  The pixel signal for one field / frame read from the image sensor 32 is converted into a digital signal by the AD converter 33 and then temporarily stored in the image memory 35. The image processing circuit 34 performs color interpolation processing, gamma correction processing, white balance adjustment, and the like on the pixel signal for one field / frame to generate a color image signal. The system control circuit 40 drives a display 37 such as an LCD based on the color image signal, and thereby a through image is displayed on the display 37.

  When the release button is pressed halfway, focus adjustment is performed. The system control circuit 40 performs AF processing based on the pixel signal read from the image sensor 32. That is, the defocus amount is calculated to shift the imaging plane to the in-focus position. In addition, AF processing by multipoint ranging can be executed. The lens CPU 28 can communicate with the lens control circuit 56 via the camera side mount contact and the lens side mount, and controls the lens driving mechanism 26 based on a command from the lens control circuit 56. The lens driving mechanism 26 moves the focusing lens of the photographing optical system 22 along the optical axis direction in accordance with a control signal from the lens CPU 28. As the release button is pressed halfway, the system control circuit 40 detects the brightness of the subject based on the pixel signal read from the image sensor 32 and calculates an exposure value (shutter speed, aperture value, etc.).

  When the release button is fully pressed, the system control circuit 40 performs exposure control. Here, the shutter speed, that is, the exposure time is adjusted by the electronic shutter function of the image sensor 32. The lens CPU 28 adjusts the degree of opening of the diaphragm 23 according to the transmitted aperture value data, and adjusts the amount of light incident on the image sensor 32.

  When a pixel signal for one frame is read from the image sensor 32, the image processing circuit 34 performs white balance processing, γ correction processing, and the like on the pixel signal for one frame to generate still image data. Still image data is recorded in a removable recording medium 54 such as a memory card after being compressed or temporarily stored in the image memory 35 in an uncompressed state.

  FIG. 2 is a diagram schematically showing a laminated structure of the image sensor. FIG. 3 is a diagram illustrating an internal structure of a predetermined pixel of the image sensor.

  As shown in FIG. 2, in the imaging device 32, three photoelectric conversion layers 62B, 62G, and 62R are stacked on the silicon substrate 75 in this order from the incident side, and the insulating films 60, 61, and 62 are interposed. Intervene in. The photoelectric conversion layer 62B selectively absorbs and photoelectrically converts light corresponding to the wavelength range of B, and transmits light corresponding to light in other wavelength ranges (including G and R). The photoelectric conversion layer 62G absorbs light in a wavelength region corresponding to G, performs photoelectric conversion, and transmits light in other wavelength regions. The photoelectric conversion layer 62R absorbs and photoelectrically converts light in a wavelength region corresponding to R, and transmits light in other wavelength regions.

  Each of the photoelectric conversion layers 62B, 62G, and 62R is configured by a thin film photoelectric conversion film that selectively absorbs light in a wavelength region corresponding to B, G, and R, and performs photoelectric conversion. Consists of. For the photoelectric conversion layer 62B, for example, a perylene derivative can be used as a material, for the photoelectric conversion layer 62G, for example, quinacridone can be used as a material, and for the photoelectric conversion layer 62R, a phthalocyanine derivative can be used as a material. is there. In addition, you may shape | mold with an inorganic material and an organic inorganic mixed material instead of an organic material.

  As shown in FIG. 3, the photoelectric conversion layer 62B is sandwiched between the pixel electrode 92B and the counter electrode 91B, and charges are generated when light corresponding to B enters. The generated charges are stored in the storage diode 66B formed on the silicon substrate 75 via the plug 63. A pixel signal read circuit 74 is formed on the silicon substrate 75, and a pixel signal is read from the storage diode 66B by a drive pulse.

  The photoelectric conversion layers 62G and 62R also have a structure sandwiched between the pixel electrodes 82G and 72R and the counter electrodes 81G and 71R, respectively. Charges are stored in the storage diodes 66G and 66R via the plugs 65 and 67, respectively. The The pixel electrodes 72R, 82G, 92B and the counter electrodes 71R, 81G, 91B are formed of a transparent electrode material, and the pixel electrodes 92B, 82G, 72R and the counter electrodes 71R, 81G, 91B are two-dimensionally arranged in a matrix. As a result, the pixel region of the image sensor 32 is defined.

  The pixel regions of the photoelectric conversion layers 62B, 62G, and 62R face each other, and each pixel of the imaging element 32 has three pixel regions of the photoelectric conversion layers 62B, 62G, and 62R. A microlens array is formed on the photoelectric conversion layer 62B in accordance with the pixel position, and the light incident on each microlens enters the pixels at the same position on the photoelectric conversion layers 62B, 62G, and 62R. The photoelectric conversion layers 62B, 62G, and 62R that function as R, G, and B color filters are stacked on each pixel of the image sensor 32, so that R, G, and B pixel signals are output from each pixel of the image sensor 32. Is done. It should be noted that interpolation processing based on surrounding pixel signals is performed for pixels corresponding to the position of focus detection pixels in the captured image.

  In the present embodiment, focus detection pixels (pixel regions) are provided in the photoelectric conversion layers 62B, 62G, and 62R, and AF processing by a phase method is executed. Hereinafter, the focus detection pixels will be described with reference to FIGS.

  FIG. 4 is a diagram illustrating focus detection pixels provided in the photoelectric conversion layers 62B, 62G, and 62R, respectively. FIG. 5 is a diagram showing a divided ranging area defined in the imaging area.

  4 shows a pixel arrangement of partial areas 32B, 32G, and 32R (see FIG. 2) in the imaging area (light receiving area) IM of the imaging element 32. When a 6 × 6 pixel block BB is defined in each photoelectric conversion layer, a pair of focus detection pixels adjacent in the oblique direction are arranged as focus detection pixels.

  In the photoelectric conversion layer 62B, the focus detection pixel pair PB is arranged at the left corner of the pixel block BB. In the photoelectric conversion layer 62G, the focus detection pixel pair PG is in the center of the pixel block BB, and in the photoelectric conversion layer 62R, the focus detection. The pixel pair PR is arranged at the right corner of the pixel block BB. The focus detection pixel pairs PB, PG, and PR are arranged so as not to overlap on the same optical path.

  In the focus detection pixel pair PB, in order to form a pair of divided images according to the pupil division phase difference method, light shielding films SL and SM that shield light from half of the pixels are formed. The light shielding films SL and SM are formed at symmetrical positions so as to form a pair of divided images from each focus detection pixel pair.

  Note that the focus detection pixel pairs PB, PG, and PR are not limited to the configuration in which the focus detection pixel pairs are arranged adjacent to each other in the oblique direction, and may be adjacent to each other in the row direction and the column direction. The formation positions of the light shielding films SL and SM may be determined according to the arrangement direction of the focus detection pixel pairs so that a pair of pupil-divided images can be obtained.

  For AF processing by multipoint ranging, a plurality (here, nine) of divided ranging areas are defined for the entire imaging area IM of the imaging element 32 (see FIG. 5). When the AF process is performed, the focus detection process is performed based on the focus detection pixel pairs PB, PG, and PR belonging to the divided ranging area where the target subject is projected.

  FIG. 6 is a flowchart of the focus detection process executed by the system control circuit 40. FIG. 7 is a diagram showing chromatic aberration.

  In step S101, the average value of the pixel signals of each photoelectric conversion layer is calculated for the divided ranging area (for example, (2, 2 in FIG. 5)) to be AF target. In step S102, the pixel signal average values of the photoelectric conversion layers 62B, 62G, and 62R are respectively compared, and it is determined whether or not the pixel signal average value of the photoelectric conversion layer 62B corresponding to B is the largest.

  Chromatic aberration occurs in the photographing optical system 22, and the imaging position differs depending on the wavelength of incident light. The shorter the wavelength, the closer the imaging position is to the photographing optical system 22 side (see FIG. 7). The wavelength range of light reflected from the subject and incident on the taking lens 20, that is, the color of the subject follows the spectral distribution characteristics of the light source and the spectral reflectance of the subject, and therefore the difference between the color of the subject and the light source (natural light and room light) The imaging position is affected by differences).

  In the image sensor 32, the photoelectric conversion layers 62B, 62G, and 62R are stacked in accordance with the difference in image formation position due to the chromatic aberration (the longer the wavelength of light, the farther from the lens). That is, the photoelectric conversion layer 62B is closest to the photographing optical system 22 side (incident side), and the photoelectric conversion layer 62G and the photoelectric conversion layer 62R are stacked in this order. The intervals between the photoelectric conversion layers 62B, 62G, and 62R are determined according to the amount of chromatic aberration.

  Therefore, when the pixel signal average outputs of the photoelectric conversion layers 62B, 62G, and 62R are compared, the imaging position is at or near the position in the depth direction (along the optical axis) of the photoelectric conversion layer having the highest output level. Can be considered. For example, when the subject is bluish, the imaging position is determined at or near the photoelectric conversion layer 62B.

  In step S102, when the average output value of the pixel signal of the photoelectric conversion layer 62B corresponding to B is the largest, the focus detection pixel pair provided in the predetermined divided distance measurement area of the photoelectric conversion layer 62B is selected and used for focus detection. A defocus amount is detected from the divided pupil image formed on the pixel, and a focusing operation is performed (S103).

  On the other hand, when the average output value of the pixel signal of the photoelectric conversion layer 62G corresponding to G is the largest, a focus detection pixel provided in the photoelectric conversion layer 62G is selected and AF processing is performed (S104, S105). Alternatively, when the average output value of the pixel signal of the photoelectric conversion layer 62R corresponding to R is the largest, a focus detection pixel provided in the photoelectric conversion layer 62R is selected and AF processing is performed (S106).

  As described above, according to the present embodiment, the single-plate multilayer imaging element 32 in which the plurality of photoelectric conversion layers 62B, 62G, and 62R are stacked on the silicon substrate 75 in this order from the incident side is provided. The focus detection pixel pair PB, PG, and PR are arranged in FIG. Then, the pixel signal average values of the photoelectric conversion layers 62B, 62G, and 62R are compared, and AF processing is performed using the focus detection pixels of the photoelectric conversion layer that output the largest average value.

  By calculating the defocus amount using the focus detection pixels of the main color component of the subject, it is possible to reduce the influence of chromatic aberration and suppress the focus detection error amount. Further, since one photoelectric conversion layer is selected and the focus detection pixels of the other photoelectric conversion layers are not used, accurate AF processing can be performed in a short time.

  Note that a representative value other than the average value (such as a median value) may be calculated for the divided ranging area. Further, the present invention can be applied to ranging methods other than multipoint ranging.

  Next, a second embodiment will be described with reference to FIGS. In the second embodiment, a photoelectric conversion layer corresponding to infrared light (IR) is provided. Other configurations are substantially the same as those in the first embodiment.

  FIG. 8 is a diagram illustrating the stacking of photoelectric conversion layers in the second embodiment. In the imaging element 32 ', in addition to photoelectric conversion layers 62B, 62G, and 62R corresponding to R, G, and B, a photoelectric conversion layer 62IR corresponding to IR is stacked. The photoelectric conversion layer 62IR is provided on the silicon substrate 75, and is configured as a Si photodiode. The photoelectric conversion layer 62IR selectively absorbs light corresponding to infrared light and performs photoelectric conversion. Similar to the other photoelectric conversion layers, transparent pixel electrodes and counter electrodes are arranged to face each other, and charges are sent to the storage diode via the plug.

  FIG. 9 is a flowchart of focus detection processing in the second embodiment.

  The execution of steps S201 to S205 is the same as the execution of steps S101 to S105 in FIG. When the average output value of the pixel signal of the photoelectric conversion layer 62R corresponding to R is the largest, a focus detection pixel provided in the photoelectric conversion layer 62R is selected, and AF processing is executed (S206, S207). On the other hand, when the average output value of the pixel signal of the photoelectric conversion layer 62IR corresponding to IR is the largest, the focus detection pixel provided in the photoelectric conversion layer 62IR is selected, and AF processing is executed (S206, S208).

  By further stacking the silicon photodiodes in this way, it is possible to suppress the influence of chromatic aberration on a subject having a color close to near infrared light.

  Next, a third embodiment will be described with reference to FIG. In the third embodiment, focus detection pixels of each photoelectric conversion layer are used, and weighting is performed according to a difference in pixel signal output level of each photoelectric conversion layer.

  FIG. 10 is a flowchart of focus detection processing in the third embodiment.

  In step S301, pixel signal average outputs Vb, Vg, and Vr of each photoelectric conversion layer are calculated for the divided ranging area to be an AF target. At the same time, defocus amounts fb, fg, and fr are calculated using the focus detection pixels of each photoelectric conversion layer (S302 to S304). Then, a weighting coefficient is determined according to the calculated ratio (ratio) of Vb, Vg, and Vr, and a final defocus amount is calculated (S305). Specifically, fb, fg, and fr are multiplied by Vb / (Vb + Vg + Vr), Vg / (Vb + Vg + Vr), and Vr / (Vb + Vg + Vr), respectively, and added.

  By performing weighted interpolation processing in this way, even when the color of the subject straddles R, G, and B color components, it is possible to reliably reduce the influence of chromatic aberration and accurately calculate the defocus amount. can do.

  In the third embodiment, the focus detection processing using the focus detection pixel signals of all photoelectric conversion layers is performed by weighting. However, the output level of the focus detection pixel signal of each photoelectric conversion layer is set by a calculation method other than weighting. You may adjust. Moreover, you may calculate using the pixel for a focus detection of two photoelectric conversion layers among three photoelectric conversion layers.

  It is also possible to form a photoelectric conversion layer that selectively absorbs light in a wavelength region other than R, G, and B, and the color image may be obtained from pixel signals of a plurality of photoelectric conversion layers. In this case, the light in the absorption wavelength region may be stacked along the optical path in the order of a short layer to a long layer. On the other hand, the subject color is not necessarily occupied by the main color, and there are some subjects in which a plurality of colors are mixed at random. .

  The focus detection process may be performed using the focus detection pixels provided in a specific photoelectric conversion layer without performing the adjustment process such as the selection or weighting of the focus detection pixels described above. In consideration of preventing the detection error amount from increasing due to the difference in the color of the subject, instead of selecting and adjusting any of the layers, a layer in which the focus detection pixels are installed may be determined in advance. For example, a focus detection processing pixel may be provided by providing a focus detection western pixel in a G photoelectric conversion layer at an intermediate position between B on the short wavelength side and R on the long wavelength side. Thereby, the focus detection error amount can be suppressed as compared with R and B for any subject color. Furthermore, if a focus detection pixel is provided in a photoelectric conversion layer that absorbs light with the shortest wavelength among the plurality of photoelectric conversion layers and a photoelectric conversion layer other than the photoelectric conversion layer that absorbs light with the longest wavelength. Good.

  In the first to third embodiments, a structure in which a plurality of photoelectric conversion layers are stacked on a single substrate is employed, but the fact that the penetration depth of light in the silicon substrate differs for each wavelength is utilized. Then, a semiconductor structure in which photodiodes that photoelectrically convert light in R, G, B, or other wavelength ranges may be employed.

10 Digital Camera 32 Image Sensor 40 System Control Circuit 62B Photoelectric Conversion Layer 62G Photoelectric Conversion Layer 62R Photoelectric Conversion Layer PB Focus Detection Pixel Pair PG Focus Detection Pixel Pair PR Focus Detection Pixel Pair

Claims (13)

An imaging device in which a plurality of photoelectric conversion layers that photoelectrically convert light in different wavelength ranges are stacked;
A focus detection unit that performs a focus detection process based on a focus detection pixel signal output from a focus detection pixel provided in each photoelectric conversion layer;
The focus detection unit selects a focus detection pixel signal or adjusts the focus detection pixel signal so as to suppress a focus detection error based on a difference in pixel signal levels output from the plurality of photoelectric conversion layers. An imaging device.   2. The focus detection unit according to claim 1, wherein the focus detection unit performs a focus detection process using a focus detection pixel of a photoelectric conversion layer that outputs the largest pixel signal among the plurality of photoelectric conversion layers. Imaging device.   2. The imaging according to claim 1, wherein the focus detection unit weights the pixel signal of each photoelectric conversion layer according to a ratio or a ratio of pixel signal levels in the plurality of photoelectric conversion layers. apparatus.   The plurality of photoelectric conversion layers are arranged in the order of a photoelectric conversion layer having a short photoelectric conversion wavelength range to a photoelectric conversion layer having a long photoelectric conversion wavelength range along the optical path. The imaging device described in 1.   The plurality of photoelectric conversion layers include a photoelectric conversion layer that photoelectrically converts light according to B, a photoelectric conversion layer that photoelectrically converts light according to G, and a photoelectric conversion layer that photoelectrically converts light according to R. The imaging device according to claim 1, wherein the imaging device is provided.   The imaging apparatus according to claim 5, wherein the plurality of photoelectric conversion layers include a photoelectric conversion layer that photoelectrically converts light corresponding to IR. Each photoelectric conversion layer has a focus detection pixel in each of a plurality of divided ranging areas defined according to the ranging points of the imaging area,
The imaging apparatus according to claim 1, wherein the focus detection unit selects a focus detection pixel signal or adjusts a focus detection pixel signal for a target divided ranging area. . Each photoelectric conversion layer has at least one pair of focus detection pixels provided with light shielding films at symmetrical positions,
The imaging apparatus according to claim 1, wherein the focus detection unit performs focus detection by a phase difference method. Focus detection processing is performed based on a focus detection pixel signal output from a focus detection pixel provided in each photoelectric conversion layer of an imaging element in which a plurality of photoelectric conversion layers that transmit light in different wavelength ranges are stacked. A focus detection device,
A focus detection device that selects a focus detection pixel signal or adjusts a focus detection pixel signal so as to suppress a focus detection error based on a difference in pixel signal levels output from the plurality of photoelectric conversion layers. . Focus detection processing is performed based on the focus detection pixel signal output from the focus detection pixel provided in each photoelectric conversion layer of the image sensor in which a plurality of photoelectric conversion layers that photoelectrically convert light in different wavelength ranges are stacked. A focus detection method to perform,
A focus detection method comprising adjusting a focus detection pixel signal or selecting a focus detection pixel signal so as to suppress a focus detection error based on a difference between pixel signal levels output from the plurality of photoelectric conversion layers. . A plurality of photoelectric conversion layers on the substrate for photoelectrically converting light in different wavelength ranges;
A pixel signal readout circuit that reads out pixel signals from the plurality of photoelectric conversion layers;
The plurality of photoelectric conversion layers are laminated,
Each photoelectric conversion layer has a focus detection pixel, and a single-plate multilayer imaging device.   The single plate type according to claim 11, wherein the plurality of photoelectric conversion layers are arranged in the order of a photoelectric conversion layer having a short photoelectric conversion wavelength range to a photoelectric conversion layer having a long photoelectric conversion wavelength range along the optical path. Multi-layer image sensor. A plurality of photoelectric conversion layers on the substrate for photoelectrically converting light in different wavelength ranges;
A pixel signal readout circuit that reads out pixel signals from the plurality of photoelectric conversion layers;
The plurality of photoelectric conversion layers are laminated,
The plurality of photoelectric conversion layers are photoelectric conversion layers other than the photoelectric conversion layer that photoelectrically converts light in the shortest wavelength region and the photoelectric conversion layer that photoelectrically converts light in the longest wavelength region, and are provided with a focus detection pixel. A single-plate multilayer imaging device comprising a conversion layer.

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