JP2011123133A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the enlargement of a ranging error even if a pixel adjacent to a focus detection pixel reaches a saturation level. <P>SOLUTION: An imaging apparatus includes: a photographic lens for forming an object image; a solid-state imaging element having a first pixel group configured to receive light passing through the pupil area of a part of the photographic lens, a second pixel group configured to receive light passing through the pupil area different from that of the first pixel group, and a third pixel group configured to receive light passing through the whole pupil area of the photographic lens; and a focus detection part configured to detect the focusing state of the photographic lens based on the first image obtained from the first pixel group and the second image obtained from the second pixel group. When the pixel constituting the third pixel group adjacent to the pixel constituting the first pixel group or the pixel constituting the second pixel group reaches the saturation level, the focus detection part is configured to set low a threshold to determine the reliability of the focus detection result. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique for detecting a focus state based on a signal obtained from a solid-state imaging device.

  As one of methods for detecting the focus state of the photographing lens, Patent Document 1 discloses a device that performs pupil division type focus detection using a two-dimensional image sensor in which a microlens is formed in each pixel. In the device of Patent Document 1, the photoelectric conversion unit of each pixel constituting the image sensor is divided into a plurality of parts, and the divided photoelectric conversion unit transmits light that has passed through different areas of the pupil of the photographing lens via the microlens. It is configured to receive light.

  Patent Document 2 discloses a solid-state imaging device that also serves as a focus detection sensor, in which pixels in which the relative positions of a microlens and a photoelectric conversion unit are displaced are two-dimensionally arranged. In the solid-state imaging device of Patent Document 2, when detecting the focus state of the photographic lens, the focus state of the photographic lens is detected based on an image generated by a pixel array having different relative displacement directions of the microlens and the photoelectric conversion unit. is doing. On the other hand, when a normal image is captured, an image is generated by adding pixels having different relative displacement directions between the microlens and the photoelectric conversion unit.

  The solid-state imaging device described in Patent Document 3 has a configuration in which some of the many pixels constituting the solid-state imaging device have a photoelectric conversion unit divided into two in order to detect the focus state of the photographing lens. ing. The photoelectric conversion unit is configured to receive light that has passed through a predetermined region of the pupil of the photographing lens via the microlens.

  FIG. 8 is an explanatory diagram of a light reception distribution of a pixel that performs focus detection located in the center of the solid-state imaging device disclosed in Patent Document 3, and shows a photographing lens that can be received by each of the two photoelectric conversion units. The area on the pupil is shown. In the figure, the hatched portion in the circle indicates the exit pupil of the photographic lens, and the white area Sα and the area Sβ are areas that can be received by the photoelectric conversion unit divided into two, and the optical axis of the normal photographic lens (see FIG. It is set to be symmetric with respect to the intersection of the middle x axis and the y axis.

  The camera detects the focus state of the photographic lens by performing a correlation operation between the image generated by the light beam transmitted through the region Sα on the pupil of the photographic lens and the image generated by the light beam transmitted through the region Sβ. A method of performing focus detection by performing correlation calculation of images generated from light beams transmitted through different pupil regions of the photographing lens is disclosed in Patent Document 4.

JP 58-24105 (2nd page, FIG. 1) Japanese Patent No. 2959142 (2nd page, FIG. 2) Japanese Patent Laying-Open No. 2005-106994 (page 7, FIG. 3) JP-A-5-127074 (page 15, FIG. 34)

  The focus detection pixel has a limited pupil area where light can be received, and therefore has a smaller output than the adjacent normal pixel. Therefore, it is more susceptible to crosstalk from adjacent pixels. This crosstalk is caused by the optical factor that the light ray incident on the adjacent pixel of the focus detection pixel leaks into the photoelectric conversion unit of the focus detection pixel, and the photoelectrons generated inside the silicon substrate of the adjacent pixel enter the focus detection pixel. It is caused by electronic factors that diffuse and mix. The problem of the present invention regarding this crosstalk will be described below with reference to FIGS.

  FIG. 9 is a graph showing the relationship between the luminance value of the subject and the output value of the focus detection pixel, and FIG. 10 is a diagram showing the focus detection image. In FIG. 9, the vertical axis represents the output value of the focus detection pixel, and the horizontal axis represents the luminance of the subject. CNT_A represents the output value of the focus detection pixel Pα1, and CNT_B represents the output value of the focus detection pixel Pβ1 paired with the focus detection pixel Pα1. In FIG. 9, the pixels adjacent to the focus detection pixels do not reach the saturation level until the luminance level is from LVL1 to LVL3. At this time, the ratio of the output value CNT_A of the focus detection pixel Pα1 and the output value CNT_B of the focus detection pixel Pβ1 varies depending on the vignetting state of each pupil region, but the ratio is constant. FIG. 10A shows a focus detection image generated from the focus detection pixel. IMG_A1 is a focus detection image obtained from the focus detection pixel Pα1, and IMG_B1 is obtained from the focus detection pixel Pβ1. It is a focus detection image. At this time, the average value of the output value CNT_A of the focus detection pixel Pα1 is AVE_A, the average value of the output value CNT_B of the focus detection pixel Pβ1 is AVE_B, and the coefficient k = AVE_A / AVE_B. Then, when the focus detection image IMG_B1 is multiplied by this coefficient k to be a focus detection image IMG_B2, as shown in FIG. 10B, the focus detection image IMG_A1 and the focus detection image IMG_B2 have no level difference. The same shape. Therefore, the focus state can be accurately detected by performing a correlation calculation between the focus detection image IMG_A1 and the focus detection image IMG_B2.

  However, when the pixel adjacent to the focus detection pixel reaches the saturation level, a change occurs in the ratio between the output value CNT_A of the focus detection pixel Pα1 and the output value CNT_B of the focus detection pixel Pβ1. In FIG. 9, when the luminance level of the subject is LVL_4, the pixels adjacent to the focus detection pixels reach the saturation level. At this time, the ratio of the output value CNT_B of the focus detection pixel Pβ1 to the output value CNT_A of the focus detection pixel Pα1 is large. FIG. 10C shows a focus detection image generated from the focus detection pixel. IMG_A1 is a focus detection image obtained from the focus detection pixel Pα1, and IMG_B3 is obtained from the focus detection pixel Pβ1. It is a focus detection image. As shown in FIG. 10C, the focus detection image IMG_A1 and the focus detection image IMG_B3 are compared with the case where the pixel adjacent to the focus detection pixel shown in FIG. 10A does not reach the saturation level. The level difference is small. Therefore, when the focus detection image IMG_B3 is multiplied by the coefficient k obtained as described above up to the luminance level LVL_3, when this is used as the focus detection image IMG_B4, as shown in FIG. The level difference remains in the detection image IMG_A1 and the focus detection image IMG_B4, and they do not have the same shape. For this reason, the CPU may determine that focus detection is impossible because the difference between the focus detection image IMG_A1 and the focus detection image IMG_B4 is large. Further, in FIG. 9, when the luminance level of the subject becomes LVL_5 higher than LVL_4, the ratio between the output value CNT_A of the focus detection pixel Pα1 and the output value CNT_B of the focus detection pixel Pβ1 further changes, and thus is multiplied by a coefficient. The level difference between subsequent focus detection images becomes even larger, increasing the possibility that focus detection will become impossible.

  As described above, conventionally, there is a problem that focus detection may be disabled when a pixel adjacent to the focus detection pixel reaches a saturation level.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to prevent the focus detection from becoming impossible even when the pixel adjacent to the focus detection pixel reaches the saturation level. It is.

  An imaging apparatus according to the present invention includes a photographing lens for forming a subject image, a first pixel group that receives light that has passed through a part of a pupil region of the photographing lens, and the first pixel group. Is a solid-state imaging device having a second pixel group that receives light that has passed through different pupil regions, and a third pixel group that receives light that has passed through all pupil regions of the photographing lens, and the first pixel Focus detection means for detecting a focus state of the photographing lens based on a first image obtained from the group and a second image obtained from the second pixel group, and constituting the first pixel group When the pixel constituting the third pixel group adjacent to the pixel constituting the second pixel group or the pixel constituting the second pixel group reaches a saturation level, the focus detection means determines the reliability of the focus detection result. The threshold value is set low.

  According to the present invention, it becomes possible to prevent the focus detection from becoming impossible even when the pixel adjacent to the focus detection pixel reaches the saturation level.

It is a figure which shows the structure of the digital camera concerning 1st Embodiment of this invention. It is a partial top view of an image sensor. It is a partial sectional view of an image sensor. It is a partial sectional view of an image sensor. It is a figure which shows the structure of the pixel for focus detection, and an adjacent pixel. It is a flowchart which shows the focus detection operation | movement in 1st Embodiment. It is a flowchart which shows the focus detection operation | movement in 2nd Embodiment. It is explanatory drawing of the light reception distribution of the pixel which performs the focus detection located in the center of the conventional solid-state imaging device. 6 is a graph showing a relationship between a luminance value of a subject and an output value of a focus detection pixel. It is a figure showing the image for focus detection.

(First embodiment)
FIG. 1 is a diagram showing a configuration of a digital camera which is an image pickup apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 10 denotes an image sensor (solid-state imaging device), which is arranged on a predetermined image formation surface of the photographing lens 5 of the camera body 1 of the digital camera. The camera body 1 includes a camera CPU 20 that controls the entire camera, and an image sensor control circuit 21 that is a control unit that drives and controls the image sensor 10. Further, an image processing circuit 24 that performs image processing on an image signal captured by the image sensor 10, a liquid crystal display element 9 that is a display means for displaying an image processed image, and a liquid crystal display element drive that drives the liquid crystal display element 9. A circuit 25 is provided. Further, an eyepiece 3 for observing the subject image displayed on the liquid crystal display element 9, a memory circuit 22 for recording an image picked up by the image sensor 10, and an image processed by the image processing circuit 24 as a camera. An interface circuit 23 for outputting to the outside is provided. The memory circuit 22 can also store the light distribution of the image sensor 10.

  The photographic lens 5 is detachable from the camera body 1 and is shown with two lenses 5a and 5b for convenience, but is actually composed of a large number of lenses. The photographic lens 5 receives the focus adjustment information sent from the camera CPU 20 of the camera body 1 by the lens CPU 50 via the electrical contact 26, and is brought into a focused state by the photographic lens driving mechanism 51 based on the focus adjustment information. Adjusted. Reference numeral 53 denotes an aperture device disposed in the vicinity of the pupil of the photographic lens 5 so that the aperture is driven to a predetermined aperture value by the aperture drive mechanism 52. The camera CPU 20 also serves as a focus detection calculation unit that calculates the focus state of the photographing lens 5.

  FIG. 2 is a partial plan view of an image sensor which is a CMOS type solid-state imaging device of the present embodiment. In the figure, 131 and 132 are electrodes. The area delimited by the electrodes 131 and 132 represents one pixel, and the letters “R”, “G”, and “B” written in one pixel represent the hue of the color filter of each pixel. Pixels with the letter “R” transmit red component light, pixels with the letter “G” transmit green component light, and pixels with the letter “B” written Transmits blue component light. In addition, each pixel on which the characters “R”, “G”, and “B” are written is configured to receive light that has passed through the entire pupil region of the photographic lens 5.

  When the color filter array is a Bayer array, one pixel is composed of “R” and “B” pixels and two “G” pixels, but the image sensor that constitutes the digital camera of this embodiment is “R”. Alternatively, focus detection pixels that receive light that has passed through a part of the pupil region of the photographic lens 5 are assigned to some of the pixels that should be “B”. In the figure, Pα 1, Pβ 1, Pα 2, and Pβ 2 are pixels for detecting the focus state of the taking lens 5, and the aperture in the x direction is restricted by the electrode 131.

  FIG. 3 is a cross-sectional view of the A-A ′ plane shown in the partial plan view of the image sensor 10 of FIG. 2. The right pixel in FIG. 3 indicates pixels (third pixel group) that can receive the entire pupil region of the photographic lens 5, and the left pixel in the drawing indicates a light beam from a part of the pupil region of the photographic lens 5. A focus detection pixel capable of receiving light is shown.

  In the image sensor 10, a photoelectric conversion unit 111 is formed inside a silicon substrate 110. The signal charge generated in the photoelectric conversion unit 111 is output to the outside through a floating diffusion unit (not shown), the first electrode 131 and the second electrode 132 (shown in FIG. 4). An interlayer insulating film 121 is formed between the photoelectric conversion unit 111 and the electrode 131, and an interlayer insulating film 122 is formed between the electrode 131 and the electrode 132 shown in FIG. 4 formed thereon. In addition, an interlayer insulating film 123 is formed on the light incident side of the electrode 132 shown in FIG. 4, and a passivation film 140 and a planarizing layer 150 are further formed. On the light incident side of the planarization layer 150, a color filter layer 151, a planarization layer 152, and a microlens 153 are formed. Here, the power of the microlens 153 is set so that the pupil of the photographing lens 5 and the photoelectric conversion unit 111 are substantially conjugate. Further, in the pixel located at the center of the image sensor 10, the microlens 153 is disposed at the center of the pixel, and at the pixels located at the periphery, the microlens 153 is disposed offset to the optical axis side of the photographing lens 5.

  The subject light transmitted through the photographing lens 5 is condensed near the image sensor 10. Further, the light reaching each pixel of the image sensor 10 is refracted by the microlens 153 and collected on the photoelectric conversion unit 111. In the pixel on the right side of FIG. 3 used for normal imaging, a first electrode 131 and a second electrode 132 are provided so as not to block incident light.

  On the other hand, in the pixel that performs focus detection of the photographic lens 5 on the left side in FIG. 3, a part of the electrode 131 is configured to cover the photoelectric conversion unit 111. As a result, the focus detection pixel on the left side of the drawing can receive a light beam that passes through a part of the pupil of the photographing lens 5. Further, in order to prevent the output of the photoelectric conversion unit 111 from being reduced because the electrode 131 blocks a part of the incident light beam, the color filter layer 154 of the focus detection pixel has high transmittance that does not absorb light. It is made of resin.

  The focus detection pixels arranged in a part of the image sensor 10 of the present embodiment have different light reception distributions of the photographing lens 5 by making the relative positions of the microlens 153 and the opening center of the electrode 131 different. It is configured to let you.

  FIG. 4 is a cross-sectional view of the B-B ′ plane shown in the partial plan view of the image sensor 10 of FIG. 2. The right pixel in FIG. 4 indicates a pixel that can receive the entire pupil region of the photographic lens 5, and the left pixel in the drawing indicates a focus detection pixel that can receive a light beam from a partial pupil region of the photographic lens 5. Is shown. The same components as those shown in FIG.

  The difference from the cross-sectional view of the A-A ′ plane shown in FIG. 3 is that the electrode 132 exists in the interlayer insulating film 123 and the electrode 131 does not exist in the interlayer insulating film 122. As shown in FIG. 3, the electrode 131 in the focus detection pixel is formed so as to cover the photoelectric conversion unit 111 in order to limit the pupil region to receive light. However, the electrode 132 is disposed so as not to block incident light in both the pixel capable of receiving the entire pupil region and the focus detection pixel.

  FIG. 5 is a diagram schematically showing a certain focus detection pixel and pixels around the focus detection pixel. Neighboring pixels 503_1 to 503_1 included in the pixel group (third pixel group) 503 shown in FIG. 5 are four directions in the vertical and horizontal directions of the focus detection pixel 501_1 included in the focus detection pixel group (first pixel group) 501. The focus detection pixel (second pixel group) 502_1 is arranged diagonally to the left of the focus detection pixel 501_1. Further, the near focus detection pixel 501_2 is disposed at a position 4 pixels away from the focus detection pixel 501_1, and has the same structure as the focus detection pixel 501_1. Further, adjacent pixels 503_5 to 8 are arranged in the four directions of the near focus detection pixel 501_2 in the upper, lower, left and right directions, and the near focus detection pixel 502_2 is similarly arranged obliquely above.

  The camera CPU 20, which is a part of the configuration of the digital camera according to the present embodiment, generates a first focus detection image (first pixel group) from a focus detection pixel group (first pixel group) having the same electrode opening as the focus detection pixel Pα 1. 1 image). Similarly, a second focus detection image (second image) is generated from a focus detection pixel group (second pixel group) having the same electrode opening as that of the focus detection pixel Pβ1. Further, the camera CPU 20 performs a correlation calculation based on the first focus detection image and the second focus detection image, thereby determining the focus state of the photographing lens 5 in the region where the focus detection pixels Pα1 and Pβ1 are located. To detect. Further, the camera CPU 20 sends focus adjustment information to the photographic lens driving mechanism 51 based on the focus detection result to adjust the focus of the photographic lens 5. On the other hand, during normal image capture, focus detection pixels with limited pixel electrode openings are treated as defective pixels, and interpolation processing is performed from pixels located around the focus detection pixels to generate image signals. Is done.

  FIG. 6 is a flowchart showing the focus detection operation in the present embodiment. When the shutter button of the camera body 1 is pressed and the exposure operation in the image sensor 10 is started, the light beam that has passed through the lens 5 is incident on the photoelectric conversion unit 111 of each pixel of the image sensor 10, and according to the amount of light beam The photoelectric conversion unit 111 changes to an electric signal, and a focus detection flow is started.

  In step S <b> 1, output values CNT_A and CNT_B of the focus detection pixel 501 and the focus detection pixel 502 are extracted from the charge amounts photoelectrically converted by the photoelectric conversion units 111 of the focus detection pixel 501 and the focus detection pixel 502. When the extraction is completed, the process proceeds to step S2.

  In step S2, focus detection images IMG_A1 and IMG_B1 are generated from the output values CNT_A and CNT_B extracted in step S1, as shown in the diagram representing the focus detection image in FIG. Further, correction is performed by multiplying by a coefficient for adjusting the shading state, and focus detection images IMG_A1 and IMG_B2 are generated as shown in the diagram showing the focus detection image in FIG. Specifically, the average value of the output values CNT_A of the focus detection pixels 501 is AVE_A, the average value of the output values CNT_B of the focus detection pixels 502 is AVE_B, and the coefficient k = AVE_A / AVE_B. Then, when the focus detection image IMG_B1 is multiplied by this coefficient k to be a focus detection image IMG_B2, as shown in FIG. 10B, the focus detection image IMG_A1 and the focus detection image IMG_B2 have no level difference. The same shape. Therefore, the focus state can be accurately detected by performing a correlation calculation between the focus detection image IMG_A1 and the focus detection image IMG_B2. When the generation of the focus detection images IMG_A1 and IMG_B1 is completed, the process proceeds to step S3.

  In step S3, output values of pixels adjacent to the focus detection pixel 501 and the focus detection pixel 502 are predicted from the output values CNT_A and CNT_B extracted in step S1. The focus detection pixel and the adjacent pixel can be roughly predicted from the relationship between the area ratio of the received pupil region and the transmittance ratio of the color filter layers 151 and 154 in the pixel. It is determined whether or not the output values of the predicted focus detection pixel 501 and the pixel adjacent to the focus detection pixel 502 have reached the saturation level. When the determination is finished, the process proceeds to step S4.

  In step S4, a parameter for determining the reliability of the focus detection result is set based on the result of step S3. The set parameter is a threshold value of the image coincidence in the correlation calculation representing the reliability of the focus detection result. As described above, when the pixels adjacent to the focus detection pixels do not reach the saturation level, there is no level difference between the focus detection image IMG_A1 and the focus detection image IMG_B2, and they have the same shape. Therefore, in the correlation calculation, the degree of coincidence between the two images when the image is shifted by an amount corresponding to defocus is large, and the reliability of the focus detection result is high. On the other hand, when the pixels adjacent to the focus detection pixels reach the saturation level, the focus detection image IMG_A1 and the focus detection image IMG_B2 have a level difference and do not have the same shape. Therefore, in this embodiment, when the pixel adjacent to the focus detection pixel is saturated, it is determined that focus detection is impossible when performing correlation calculation between the focus detection image IMG_A1 and the focus detection image IMG_B2. The threshold value of the matching degree of images to be reduced is lowered. Accordingly, focus detection can be performed even when the degree of coincidence between the focus detection image IMG_A1 and the focus detection image IMG_B2 is low. However, on the other hand, the focus detection result obtained by lowering the threshold value of image coincidence is unreliable. For this reason, in this embodiment, when the threshold value of the degree of coincidence of images is set low as described later, the driving amount of the lens by the photographing lens driving mechanism 51 is reduced. When the parameter setting is completed, the process proceeds to step S5.

  In step S5, the camera CPU 20 performs a distance measurement calculation using the focus detection images IMG_A1 and IMG_B2 generated in step S2. The focus detection images IMG_A1 and IMG_B2 are shifted relative to each other in the correlation direction, and a shift amount with the highest degree of coincidence of images is calculated. When the deviation amount calculation is completed, the process proceeds to step S6.

  In step S6, reliability is determined. If the degree of coincidence between the focus detection images IMG_A1 and IMG_B2 generated in step S2 is less than the image coincidence threshold set in step S4, it is determined that distance measurement is impossible, and the process proceeds to step S9. On the other hand, when the coincidence degree between the focus detection images IMG_A1 and IMG_B2 is equal to or larger than the image coincidence threshold set in step S4, the process proceeds to step S7.

  In step S7, in-focus determination is made. If the amount of deviation calculated in step S5 is less than or equal to the set focus range, it is determined that the in-focus state is reached, and the process proceeds to step S10. If the amount of deviation calculated in step S5 is out of the set focusing range, it is determined that the in-focus state is not set, and the process proceeds to step S8.

  In step S <b> 8, the camera CPU 20 calculates a corresponding defocus amount from the shift amount calculated in step S <b> 5 and transmits it to the lens CPU 50 via the electrical contact 26. Based on the focus adjustment information, the lens is driven so as to be brought into focus by the photographic lens driving mechanism 51. At this time, when the threshold for determining the reliability of the focus detection result set in step S4 (threshold for image coincidence) is low, since the reliability of the focus detection result is low, the lens obtained from the focus adjustment information Driving is performed by an amount obtained by multiplying the driving amount by a coefficient of 1 or less. When the lens driving is completed, the process proceeds to step S1.

  In step S9, the focus determination in step S6 is received and the user is notified that distance measurement is impossible. The notification may be performed by a method that can be understood by the user, such as display by the liquid crystal display element 9 or voice transmission by a speaker (not shown). When the notification to the user is completed, the process proceeds to step S10. In step S10, the focus detection mode ends and a series of sequences is completed.

  According to the configuration as described above, it is possible to prevent the focus detection from being disabled due to the pixel adjacent to the focus detection pixel reaching the saturation level.

  In this embodiment, the output of the pixel adjacent to the focus detection pixel is predicted from the output value of the focus detection pixel. However, the output value of the pixel adjacent to the focus detection pixel is extracted and reaches the saturation level. It may be determined whether or not.

(Second Embodiment)
In the first embodiment, distance measurement is impossible when the degree of coincidence of images is less than a threshold value. However, when another focus detection calculation means is provided, it may be switched to another focus detection calculation means. In the following, an embodiment in which another focus detection calculation means is provided will be described. Hereinafter, the focus detection calculation means using the signal of the focus detection pixel described in the first embodiment is referred to as a first focus detection calculation means (first focus detection means), and the first focus detection calculation means and Different focus detection calculation means are referred to as second focus detection calculation means (second focus detection means).

  Since the main configuration of the digital camera in the present embodiment is the same as that of the first embodiment, illustration and description are omitted. However, the camera CPU 20 also serves as second calculation means for detecting the focus of the subject based on the contrast information of the captured image (third image) obtained from the third pixel group.

  FIG. 7 is a flowchart showing the focus detection operation of this embodiment. Since steps other than step S104 and step S109 are the same as those in FIG. 6 of the first embodiment, description thereof will be omitted.

  In step S104, when a pixel adjacent to the focus detection pixel is saturated, an image that is determined to be incapable of focus detection when performing a correlation calculation between the focus detection image IMG_A1 and the focus detection image IMG_B2. Increase the threshold of coincidence. As a result, when the pixels adjacent to the focus detection pixels are saturated and the degree of coincidence between the focus detection image IMG_A1 and the focus detection image IMG_B2 is low, forcibly, as described later, the second Focus detection calculation is performed by the focus detection calculation means.

  If the image coincidence degree is lower than the threshold value set high in step S104 in step S106, the process proceeds to step S109. In step S109, the camera CPU 20 starts the second focus detection. The CPU 20 calculates the contrast information of the captured image by a known method and determines the focus state. When the focusing operation by the second focus detection calculating means is completed, the process proceeds to step S110. In step S110, the focus detection mode ends and a series of sequences is completed.

  According to the above configuration, when the pixel adjacent to the focus detection pixel reaches the saturation level, focus detection is performed by the second focus detection calculation unit, and focus detection under a wider shooting condition is performed. Is possible.

Claims (3)

A photographic lens for forming a subject image;
A first pixel group that receives light that has passed through a part of the pupil region of the photographic lens; a second pixel group that receives light that has passed through a pupil region different from the first pixel group; A solid-state imaging device having a third pixel group that receives light that has passed through the entire pupil region of the lens;
A focus detection unit that detects a focus state of the photographing lens based on a first image obtained from the first pixel group and a second image obtained from the second pixel group;
When the pixels constituting the first pixel group or the pixels constituting the third pixel group adjacent to the pixels constituting the second pixel group reach a saturation level, the focus detection means An imaging apparatus, wherein a threshold value for determining reliability of a detection result is set low.   When the pixels constituting the first pixel group or the pixels constituting the third pixel group adjacent to the pixels constituting the second pixel group reach a saturation level, the focus detection means The imaging apparatus according to claim 1, wherein no detection is performed.   A second focus detection unit configured to detect a focus state based on a contrast of a third image obtained from the third pixel group; and pixels constituting the first pixel group or the second pixel group 2. The focus detection is performed by the second focus detection unit when a pixel constituting the third pixel group adjacent to the pixel constituting the pixel reaches a saturation level. Imaging device.

Images