Image pickup element and image pickup device

Abstract

To provide an imaging element capable of performing focus detection even during a large defocus.SOLUTION: An imaging element includes a plurality of first pixel rows having a plurality of first pixels for receiving light transmitted through an image formation optical system and outputting a signal used for the focus detection, a plurality of second pixel rows having a plurality of second pixels for receiving the light transmitted through the image formation optical system and outputting the signal used for the focus detection, and a circuit for selecting any one of the first pixel rows and the second pixel rows on the basis of information relating to an exit pupil position of the image formation optical system. The first pixels receive the light through an opening provided in the first position of a light shielding part and the second pixels receive the light through an opening provided in a second position different from the first position of the light shielding part. The imaging element includes a first area in which only one of the plurality of first pixel rows and the plurality of second pixel rows is arranged and a second area whose image height is higher than that of the first area and in which both of the plurality of first pixel rows and the plurality of second pixel rows are arranged.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an imaging element and an imaging device. [Background technology]

[0002] Image sensors that have focus detection pixels on the imaging surface for performing split-pupil focus detection have been known for some time. However, there has been a problem with focus detection when the image is significantly out of focus (large defocus). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-106994 Summary of the Invention

[0004] According to the first aspect, the image sensor receives light transmitted through the imaging optical system and outputs a signal used for focus detection. and arranged along the first direction a plurality of first pixel columns each having a plurality of first pixels, and a signal output unit configured to receive light transmitted through the imaging optical system and output a signal used for focus detection; and arranged along the first direction a plurality of second pixel columns each having a plurality of second pixels; a plurality of third pixels that receive light transmitted through the imaging optical system and output signals used for imaging; a circuit for selecting either the first pixel row or the second pixel row based on information about an exit pupil position of the imaging optical system; An imaging element the first pixel receives light through an opening provided at a first position of the light-shielding portion, and the second pixel receives light through an opening provided at a second position of the light-shielding portion that is different from the first position; The imaging element is Either one of the plurality of first pixel columns or the plurality of second pixel columns and the third pixel a first region in which only the a region having the same size as the first region than in the first direction When the image height is high, both the plurality of first pixel rows and the plurality of second pixel rows and the third pixel and a second region in which the According to a second aspect, an imaging device receives light transmitted through an imaging optical system and outputs a signal used for focus detection. and arranged along the first direction a plurality of first pixel columns each having a plurality of first pixels, and a signal output unit configured to receive light transmitted through the imaging optical system and output a signal used for focus detection; and arranged along the first direction a plurality of second pixel columns each having a plurality of second pixels; a plurality of third pixels that receive light transmitted through the imaging optical system and output signals used for imaging; and a detection unit that selects one of the first pixel row and the second pixel row based on information about an exit pupil position of the imaging optical system, and detects a defocus amount using a signal from the selected pixel row. An imaging device the first pixel receives light through an opening provided at a first position of the light-shielding portion, and the second pixel receives light through an opening provided at a second position of the light-shielding portion that is different from the first position; The imaging device is Either one of the plurality of first pixel columns or the plurality of second pixel columns and the third pixel a first region in which only the a region having the same size as the first region than in the first direction When the image height is high, both the plurality of first pixel rows and the plurality of second pixel rows and the third pixel and a second region in which the [Brief explanation of the drawings]

[0005] [Figure 1] 1 is a cross-sectional view schematically showing the configuration of a camera system according to a first embodiment of the present invention. [Figure 2] 2 is a plan view schematically showing an imaging surface 20 of an imaging element 210. FIG. [Figure 3] FIG. 3 is an explanatory diagram of an imaging and focus detection pixel 301. [Figure 4] FIG. 10 is an explanatory diagram of first focus detection pixels 302NR and 302NL. [Figure 5] FIG. 10 is an explanatory diagram of second focus detection pixels 302SR and 302SL. [Figure 6] FIG. 10 is an explanatory diagram of third focus detection pixels 302LR and 302LL. [Figure 7] 2 is a plan view schematically showing an imaging surface 20 of an imaging element 210. FIG. [Figure 8]FIG. 2 is an enlarged view of a part of the first region 60a. [Figure 9] FIG. 10 is an enlarged view of a portion of the second region 60b. [Figure 10] FIG. 10 is an enlarged view of a portion of the third region 60c. [Figure 11] 10 is a flowchart of a control process executed by a body CPU 220. [Figure 12] 12 is a flowchart of the AF process called from step S30 in FIG. 11. [Figure 13] 12 is a flowchart of the AF process called from step S30 in FIG. 11. [Figure 14] FIG. 2 is a perspective view schematically showing the structure of an imaging element 210a. [Figure 15] 3 is a cross-sectional view schematically showing an imaging / focus detection pixel 301 and a focus detection pixel 302. FIG. [Figure 16] 10 is an enlarged plan view of a portion of the first region 60a of the image sensor 210a. [Figure 17] 10 is an enlarged plan view of a portion of the second region 60b of the image sensor 210a. [Figure 18] 10 is an enlarged plan view of a portion of the third region 60c of the imaging element 210a. [Figure 19] 1 is a cross-sectional view schematically showing a light beam from a light point P on an image plane S to be combined and an image sensor 210a. [Figure 20] FIG. 10 is an explanatory diagram of a first focus detection pixel according to a modified example. [Figure 21] FIG. 10 is an explanatory diagram of an imaging surface according to a modified example. [Figure 22] 10A and 10B are explanatory diagrams of imaging and focus detection pixels according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0006] (First embodiment) Fig. 1 is a cross-sectional view showing a schematic configuration of a camera system according to a first embodiment of the present invention. Fig. 1 mainly illustrates components particularly related to the present invention, and omits other components that make up camera system 1. The following description will focus on components particularly related to the present invention, and omits description of other components.

[0007] The camera system 1 is a so-called single-lens reflex digital camera. The camera system 1 is composed of an interchangeable lens 100 and a camera body 200. A user can select one of multiple types of interchangeable lenses 100 that are compatible with the camera body 200 (that can be attached to the camera body 200), attach it to the camera body 200, and take pictures. Figure 1 shows an example of one of the multiple types of interchangeable lenses 100.

[0008] The camera body 200 and the interchangeable lens 100 have, for example, a bayonet-type lens mount mechanism. The interchangeable lens 100 is attached to the camera body 200 by fitting the mount portion of the interchangeable lens 100 into the mount portion of the camera body 200.

[0009] The interchangeable lens 100 includes an imaging optical system 110, a lens CPU 120, and an aperture 130. The imaging optical system 110 is made up of a lens 111 and a focusing lens 112. The imaging optical system 110 forms a subject image on the imaging plane of an image sensor 210, which will be described later. The position of the exit pupil of the imaging optical system 110 differs depending on the type of interchangeable lens 100.

[0010] The camera body 200 includes an image sensor 210, a body CPU 220, a focus adjustment unit 230, a ROM 240, and a display device 250. The image sensor 210 is, for example, a CCD or CMOS image sensor. The image sensor 210 receives subject light that has passed through the imaging optical system 110 and outputs an image signal and a focus detection signal. The body CPU 220 is composed of a microprocessor (not shown) and its peripheral circuits. The body CPU 220 loads and executes a control program pre-stored in the ROM 240, a non-volatile storage medium, to control each unit of the camera body 200 and perform data communication with the interchangeable lens 100. The focus adjustment unit 230 includes an actuator (not shown) and adjusts the focus of the imaging optical system 110 by driving the focusing lens 112 in the optical axis direction under the control of the body CPU 220. The display device 250 is, for example, a liquid crystal display (LCD) and displays live view images, various setting screens, and the like.

[0011] The body CPU 220 is provided with a first focus detection unit 221 and a second focus detection unit 222 in the form of software. These units are realized in software form by the body CPU 220 executing a predetermined control program stored in the ROM 240.

[0012] The first focus detection unit 221 detects the focus adjustment state of the imaging optical system 110 based on focus detection signals output from imaging and focus detection pixels, which will be described later. The second focus detection unit 222 detects the focus adjustment state of the imaging optical system 110 based on focus detection signals output from focus detection pixels, which will be described later.

[0013] (Explanation of the image sensor 210) Fig. 2(a) is a plan view that schematically shows the imaging surface 20 of the imaging element 210. For ease of explanation, Fig. 2(a) sets a coordinate system in which the direction parallel to the top and bottom sides of the imaging surface 20 (left and right directions on the paper) is the X axis, the direction parallel to the left and right sides of the imaging surface 20 (up and down directions on the paper) is the Y axis, and the front and back direction of the imaging surface 20, i.e., the optical axis direction of the imaging optical system 110, is the Z axis. The same coordinate system is also set for the subsequent drawings.

[0014] 2(a) shows a vertical line OX that bisects the imaging surface 20 in the left-right direction (X-axis direction) and a horizontal line OY that bisects the imaging surface 20 in the up-down direction (Y-axis direction), superimposed on the imaging surface 20. The intersection of the vertical line OX and the horizontal line OY substantially coincides with the optical axis of the imaging optical system 110. FIG. 2(b) shows an enlarged schematic diagram of a region 20a near the center of the imaging surface 20 (near the intersection of the vertical line OX and the horizontal line OY) of the entire imaging surface 20 shown in FIG. 2(a).

[0015] As shown in Figure 2(b), a large number of pixels 30 are arranged in a two-dimensional square on the imaging surface 20. The pixels 30 include two types of pixels: imaging and focus detection pixels 301 that are used for both imaging and focus detection, and focus detection pixels 302 that are used only for focus detection, but Figure 2(b) does not distinguish between the two. Below, we will first explain the imaging and focus detection pixels 301, focusing in particular on imaging and focus detection pixel 301a that is located in the center of the imaging surface 20 (the intersection of vertical line OX and horizontal line OY).

[0016] 3(a) is an enlarged plan view of an imaging and focus detection pixel 301a located at the center of the imaging surface 20 (the intersection of the vertical line OX and the horizontal line OY) among the pixels 30 shown in FIG. 2(b), and FIG. 3(b) is a cross-sectional view of the imaging and focus detection pixel 301a. The imaging and focus detection pixel 301a includes a microlens 31, a color filter 32, and a pair of photoelectric conversion units 34L and 34R. The pair of photoelectric conversion units 34L and 34R has a substantially semicircular shape obtained by dividing a circle along the Y-axis direction. In other words, the pair of photoelectric conversion units 34L and 34R are arranged along the X-axis direction (focus detection direction). The maximum width of the pair of photoelectric conversion units 34L and 34R in the X-axis direction is W1.

[0017] The microlens 31 focuses light incident on the imaging and focus detection pixel 301a onto a pair of photoelectric conversion units 34L and 34R. This incident light is incident on the pair of photoelectric conversion units 34L and 34R via a color filter 32. The color filter 32 is formed to transmit either red, blue, or green light for each pixel and block other light. The color filters 32 of the imaging and focus detection pixel 301a are configured in a so-called Bayer array. A wiring layer 33 is provided between the color filter 32 and the pair of photoelectric conversion units 34L and 34R. The wiring layer 33 is arranged in the portion between the pixels so as not to block the light incident on the pair of photoelectric conversion units 34L and 34R.

[0018] 3(b) represents the optical axis of the microlens 31 (hereinafter referred to as the optical axis 41). In addition, dashed line 42 shown in FIG. 3(b) represents the center of the division position between the photoelectric conversion unit 34L and the photoelectric conversion unit 34R (hereinafter referred to as the division line 42). The photoelectric conversion unit 34L and the photoelectric conversion unit 34R have shapes symmetrical with respect to the division line 42 and are disposed symmetrical with respect to the division line 42.

[0019] The pair of photoelectric conversion units 34L, 34R are, for example, photodiodes, and output photoelectric conversion signals obtained by photoelectrically converting incident light. The imaging and focus detection pixel 301a separately outputs the photoelectric conversion signal output by the photoelectric conversion unit 34L and the photoelectric conversion signal output by the photoelectric conversion unit 34R. A signal obtained by adding together these pair of photoelectric conversion signals is substantially the same as the imaging signal output by a single photoelectric conversion unit that substantially matches the external shape of the pair of photoelectric conversion units 34L, 34R. In other words, the imaging and focus detection pixel 301a can output an imaging signal.

[0020] On the other hand, the photoelectric conversion signal output by the photoelectric conversion unit 34L and the photoelectric conversion signal output by the photoelectric conversion unit 34R correspond to a pair of light beams that have passed through a pair of regions of the exit pupil of the imaging optical system 110. Therefore, by detecting the phase difference between a signal made up of the photoelectric conversion signals output by the photoelectric conversion units 34R of the many imaging and focus detection pixels 301a arranged in a row along the X-axis direction (a predetermined focus detection direction, also referred to as the first direction) and a signal made up of the photoelectric conversion signals output by the photoelectric conversion units 34L of those many imaging and focus detection pixels 301a, it is possible to calculate a focus evaluation value (defocus amount) of the imaging optical system 110. In other words, the imaging and focus detection pixels 301a can also output focus detection signals capable of performing focus detection calculations using the well-known phase difference method.

[0021] As described above, the pair of photoelectric conversion units 34L, 34R of the imaging and focus detection pixel 301a output photoelectric conversion signals that are used as both an imaging signal and a split-pupil focus detection signal. Note that the process of adding the pair of photoelectric conversion signals to generate an imaging signal and the process of converting the pair of photoelectric conversion signals into a focus detection signal may be performed by the imaging and focus detection pixel 301a, a dedicated circuit provided within the image sensor 210, a dedicated circuit provided external to the image sensor 210, or the body CPU 220.

[0022] Next, we will focus on another imaging and focus detection pixel 301b (see FIG. 2(b)), which is four pixels away from the imaging and focus detection pixel 301a to the right of the page (in the +X direction). FIG. 3(c) is a cross-sectional view of the imaging and focus detection pixel 301b. Like the imaging and focus detection pixel 301a, the imaging and focus detection pixel 301b also has a microlens 31, a color filter 32, and a pair of photoelectric conversion units 34L and 34R. However, as is clear from a comparison of FIGS. 3(b) and 3(c), in the imaging and focus detection pixel 301a, the position of the optical axis 41 of the microlens 31 and the position of the division line 42 representing the center of the division of the pair of photoelectric conversion units 34L and 34R are approximately aligned in the X-axis direction, whereas in the imaging and focus detection pixel 301b, the optical axis 41 and the division line 42 are separated by a distance 40 in the X-axis direction.

[0023] Thus, in an imaging and focus detection pixel 301b located away from the center of the imaging surface 20, the optical axis 41 of the microlens 31 is spaced apart from the dividing line 42 of the pair of photoelectric conversion units 34L and 34R, and this distance 40 increases as the distance from the center of the imaging surface 20 increases. Since the light beam that has passed through the imaging optical system 110 is incident on the imaging and focus detection pixel 301b from the upper left to the lower right of the page in FIG. 3(c), the microlens 31 is positioned so as to be offset by a distance 40 that corresponds to the angle of the incident light in order to improve light collection. Note that while FIGS. 3(b) and 3(c) only describe the offset in the X-axis direction, the microlens 31 and the pair of photoelectric conversion units 34L and 34R are similarly positioned so as to be different from each other in the Y-axis direction.

[0024] Next, we will explain the focus detection pixels 302. In addition to the imaging and focus detection pixels described above, the image sensor 210 has many types of focus detection pixels: first focus detection pixels 302NL and 302NR, second focus detection pixels 302SL and 302SR, third focus detection pixels 302LL and 302LR, fourth focus detection pixels 302SNL and 302SNR, and fifth focus detection pixels 302LNL and 302LNR. The locations where these focus detection pixels are located will be described in detail later, but below we will first explain the structure of these focus detection pixels.

[0025] 4(a) is a cross-sectional view of the first focus detection pixel 302NR. The first focus detection pixel 302NR has a microlens 31, a photoelectric conversion unit 34, and a light-shielding member 35. The differences between the imaging and focus detection pixel 301b and the first focus detection pixel 302NR are that the first focus detection pixel 302NR does not have a color filter 32, has a single undivided photoelectric conversion unit 34 instead of a pair of photoelectric conversion units 34L and 34R, and has a light-shielding member 35.

[0026] The light-shielding member 35 is a thin film (light-shielding film) that blocks incident light. An opening 36NR is provided at a predetermined position (referred to as a first position) of the light-shielding member 35. Only the light beam that passes through the opening 36NR is incident on the photoelectric conversion unit 34; other light beams are blocked by the light-shielding member 35 and do not enter the photoelectric conversion unit 34. The width of the opening 36NR in the X-axis direction (focus detection direction) is W2, which is smaller than the width W1 in the X-axis direction of the photoelectric conversion units 34L and 34R shown in FIG. 3.

[0027] 4(b) is a cross-sectional view of the first focus detection pixel 302NL. The first focus detection pixel 302NL has almost the same configuration as the first focus detection pixel 302NR, and differs from the first focus detection pixel 302NR in that an opening 36NL is provided in the light blocking member 35 instead of the opening 36NR. The opening 36NL has the same size and shape as the opening 36NR, but its position on the light blocking member 35 is different from that of the opening 36NR.

[0028] The openings 36NR and 36NL are located to the left and right of the dash-dotted line 44N. In other words, the dash-dotted line 44N is a straight line that defines the division center of the openings 36NR and 36NL. In the following description, the dash-dotted line 44N will be referred to as the division line 44N. The first focus detection pixel 302NR outputs a light reception signal corresponding to the optical image of the subject formed to the right of the division line 44N, and the first focus detection pixel 302NL outputs a light reception signal corresponding to the optical image of the subject formed to the left of the division line 44N. In other words, the first focus detection pixels 302NR and 302NL each receive a pair of pupil-split light beams and output a pair of focus detection signals.

[0029] The width of the openings 36NR, 36NL in the focus detection direction (X-axis direction) is smaller than the width of the photoelectric conversion units 34R, 34L in the focus detection direction (X-axis direction) described with reference to FIGS. 3(a) to 3(c). That is, a more restricted light beam enters the photoelectric conversion units 34 of the first focus detection pixels 302NR, 302NL than the photoelectric conversion units 34R, 34L of the imaging and focus detection pixel 301. Therefore, when the defocus amount is particularly large, that is, when the subject portion targeted for focus adjustment is significantly out of focus, the focus detection signals output from the first focus detection pixels 302NR, 302NL have stronger contrast than the focus detection signals output from the imaging and focus detection pixel 301. Therefore, even when it is difficult to detect a phase difference using the focus detection signal output from the imaging and focus detection pixel 301, it is possible to detect a phase difference using the focus detection signals output from the first focus detection pixels 302NR, 302NL.

[0030] In the following description, the phrase "the width of the photoelectric conversion unit 34 in the focus detection direction (X-axis direction) is smaller than the width of the photoelectric conversion units 34R, 34L in the focus detection direction (X-axis direction)" may be used to refer to the fact that the width of the openings 36NR, 36NL in the focus detection direction is smaller than the width of the photoelectric conversion units 34R, 34L in the focus detection direction (X-axis direction). In other words, the "width of the photoelectric conversion unit 34 in the focus detection direction (X-axis direction)" does not refer to the actual width of the photoelectric conversion unit 34, but rather the width of the incidence range of incident light on the photoelectric conversion unit 34. Therefore, the phrase "the width of the photoelectric conversion unit 34 in the focus detection direction (X-axis direction) is smaller than the width of the photoelectric conversion units 34R, 34L in the focus detection direction (X-axis direction)" includes cases where the photoelectric conversion unit 34 is actually formed to have a small width and cases where a light-shielding member 35 or the like is provided so that the incidence range of light incident on the photoelectric conversion unit 34 is small.

[0031] The division line 44N substantially coincides with the division line 42 that bisects the photoelectric conversion unit 34 in the left-right direction (X-axis direction) on the page. 4(a) and (b) show a chief ray 43N, which is one of the chief rays of the exit pupil of the imaging optical system 110 and passes through the vertex of the microlens 31. The chief ray 43N forms an angle θN with the optical axis 41 of the microlens 31. The position of the division line 44N corresponds to the position of the chief ray 43N assumed by the first focus detection pixels 302NR and 302NL.

[0032] Figure 5(a) is a cross-sectional view of the second focus detection pixel 302SR, and Figure 5(b) is a cross-sectional view of the second focus detection pixel 302SL. The second focus detection pixels 302SR and 302SL have almost the same configuration as the first focus detection pixels 302NR and 302NL shown in Figures 4(a) and 4(b), respectively, and differ from the first focus detection pixels 302NR and 302NL in that openings 36SR and 36SL are provided in the light blocking member 35 instead of openings 36NR and 36NL.

[0033] The openings 36SR and 36SL have substantially the same size and shape as the openings 36NR and 36NL, respectively. The openings 36SR and 36SL are located to the left and right of the two-dot chain line 44S. In other words, the two-dot chain line 44S is a straight line that defines the dividing center of the openings 36SR and 36SL. In the following description, the two-dot chain line 44S will be referred to as the dividing line 44S.

[0034] 4(a) and 4(b), the division line 44S is located relatively to the right of the division line 44N. Therefore, the division line 44S is located at a predetermined distance to the right of the division line 42 that bisects the photoelectric conversion unit 34 in the left-right direction (X-axis direction) of the page.

[0035] 5(a) and (b) show a chief ray 43S of the exit pupil of the imaging optical system 110 that passes through the apex of the microlens 31. The chief ray 43S forms an angle θS with respect to the optical axis 41 of the microlens 31. The angle θS is larger than the angle θN shown in FIGS. 4(a) and (b). In other words, even if the exit pupil of the imaging optical system 110 is relatively close and subject light does not enter the openings 36NR and 36NL of the first focus detection pixels 302NR and 302NL, subject light still enters the openings 36SR and 36SL. The position of the division line 44S corresponds to the position of the chief ray 43S assumed by the second focus detection pixels 302SR and 302SL. Thus, the opening 36NR is located at a first position, while the opening 36SR is located at a second position different from the first position.

[0036] Figure 6(a) is a cross-sectional view of the third focus detection pixel 302LR, and Figure 6(b) is a cross-sectional view of the third focus detection pixel 302LL. The third focus detection pixels 302LR and 302LL have almost the same configuration as the first focus detection pixels 302NR and 302NL shown in Figures 4(a) and 4(b), respectively, and differ from the first focus detection pixels 302NR and 302NL in that openings 36LR and 36LL are provided in the light blocking member 35 instead of openings 36NR and 36NL.

[0037] The openings 36LR and 36LL have substantially the same size and shape as the openings 36NR and 36NL, respectively. The openings 36LR and 36LL are located on the left and right sides of the two-dot chain line 44L. In other words, the two-dot chain line 44L is a straight line that defines the dividing center of the openings 36LR and 36LL. In the following description, the two-dot chain line 44L will be referred to as the dividing line 44L.

[0038] 4(a) and 4(b), the division line 44L is located relatively to the left of the division line 44N. Therefore, the division line 44L is located at a predetermined distance to the left of the division line 42 that bisects the photoelectric conversion unit 34 in the left-right direction (X-axis direction) on the page.

[0039] 6(a) and 6(b) show a chief ray 43S of the exit pupil of the imaging optical system 110 that passes through the vertex of the microlens 31. The chief ray 43L forms an angle θL with respect to the optical axis 41 of the microlens 31. The angle θL is smaller than the angle θN shown in FIGS. 4(a) and 4(b). In other words, even if the exit pupil of the imaging optical system 110 is located relatively far away and subject light does not enter the openings 36NR and 36NL of the first focus detection pixels 302NR and 302NL, subject light still enters the openings 36LR and 36LL. The position of the division line 44L corresponds to the position of the chief ray 43L assumed by the third focus detection pixels 302LR and 302LL.

[0040] The focus detection pixels further include fourth focus detection pixels 302SNL and 302SNR (both not shown) and fifth focus detection pixels 302LNL and 302LNR (both not shown). The fourth focus detection pixels 302SNL and 302SNR correspond to the first focus detection pixels 302NL and 302NR, respectively, and the division center of the opening provided in the light blocking member 35 is located between the division line 44N of the first focus detection pixels 302NL and 302NR and the division line 44L of the third focus detection pixels 302LL and 302LR. In other words, when the exit pupil of the imaging optical system 110 is located farther away than the intended position of the first focus detection pixels 302NL and 302NR and closer than the intended position of the third focus detection pixels 302LL and 302LR, the focus detection signal can be output appropriately. The fifth focus detection pixels 302LNL and 302LNR correspond to the first focus detection pixels 302NL and 302NR, respectively, and the division center of the opening provided in the light blocking member 35 is between the division line 44N of the first focus detection pixels 302NL and 302NR and the division line 44S of the second focus detection pixels 302SL and 302SR. In other words, when the exit pupil of the imaging optical system 110 is closer than the intended position for the first focus detection pixels 302NL and 302NR and farther than the intended position for the second focus detection pixels 302SL and 302SR, the focus detection signal can be output appropriately.

[0041] As described above, the image sensor 210 has five types of focus detection pixels (first focus detection pixels 302NL and 302NR, second focus detection pixels 302SL and 302SR, third focus detection pixels 302LL and 302LR, fourth focus detection pixels 302SNL and 302SNR, and fifth focus detection pixels 302LNL and 302LNR), and these five types of focus detection pixels each have a different assumed exit pupil position. In other words, each corresponds to a different imaging optical system 110. The position of the exit pupil changes, for example, when the interchangeable lens 100 is replaced with a different type or when the zoom position of a so-called zoom lens with a variable focal length is changed. However, with the camera system 1 of this embodiment, a focus detection signal can be reliably obtained from any of the focus detection pixels regardless of the position of the exit pupil.

[0042] Next, the arrangement of the various types of focus detection pixels described above will be described. FIG. 7 is a plan view schematically showing the imaging surface 20 (i.e., the shooting screen) of the image sensor 210. Consider five regions obtained by dividing the imaging surface 20 equally in the left-right direction. Each region has a rectangular shape with its long side parallel to the vertical line OX. Of these five regions, the region including the center of the imaging surface 20 is defined as a first region 60a. Two regions adjacent to the first region 60a are defined as second regions 60b. Furthermore, the remaining two regions adjacent to the left and right edges of the imaging surface 20 are defined as a third region 60c. In this embodiment, multiple focus detection pixel rows 61, in which focus detection pixels are arranged in a row in the left-right direction (X-axis direction), are provided within the first region 60a, second region 60b, and third region 60c.

[0043] The second region 60b is longer in distance from the optical axis of the imaging optical system 110 along the left-right direction on the page (X-axis direction) than the first region 60a. That is, the second region 60b is a region with a higher image height than the first region 60a. The third region 60c is longer in distance from the optical axis of the imaging optical system 110 along the left-right direction on the page (X-axis direction) than the first region 60a and the second region 60b. That is, the third region 60c is a region with a higher image height than the first region 60a and the second region 60b.

[0044] An enlarged view of a portion of the first region 60a is shown in Fig. 8. In Fig. 8, the letters "R," "G," and "B" represent imaging and focus detection pixels 301 having red, green, and blue color filters 32, respectively, and the letters "NL" and "NR" represent first focus detection pixels 302NL and 302NR, respectively.

[0045] 8, in the focus detection pixel column 61N in the first region 60a, first focus detection pixels 302NL, 302NR are arranged alternately at regular intervals d in the left-right direction (X-axis direction). For example, from left to right, the pixels 30 are arranged as follows: first focus detection pixel 302NL, multiple imaging and focus detection pixels 301a, first focus detection pixel 302NR, multiple imaging and focus detection pixels 301a, first focus detection pixel 302NL, ... In other words, in the first region 60a, some of the imaging and focus detection pixels 301 are replaced with the first focus detection pixels 302NL, 302NR.

[0046] As shown in Fig. 7, the second region 60b has more focus detection pixel arrays 61 than the first region 60a. Fig. 9 shows an enlarged view of a portion of the second region 60b. In Fig. 9, the second focus detection pixels 302SL, 302SR and the third focus detection pixels 302LL, 302LR are represented by the letters "SL," "SR," "LL," and "LR," respectively. The second region 60b has multiple focus detection pixel arrays 61 of three types: focus detection pixel array 61N, focus detection pixel array 61S, and focus detection pixel array 61L.

[0047] In the focus detection pixel column 61N, first focus detection pixels 302NL and 302NR are alternately arranged at regular intervals d in the left-right direction (X-axis direction). In the focus detection pixel column 61S, second focus detection pixels 302SL and 302SR are alternately arranged at regular intervals d in the left-right direction (X-axis direction). In the focus detection pixel column 61L, third focus detection pixels 302LL and 302LR are alternately arranged at regular intervals d in the left-right direction (X-axis direction). In other words, within the second region 60b, some of the imaging and focus detection pixels 301 have been replaced with the first focus detection pixels 302NL and 302NR, the second focus detection pixels 302SL and 302SR, and the third focus detection pixels 302LL and 302LR.

[0048] As shown in FIG. 7, the third region 60c has more focus detection pixel arrays 61 than the second region 60b. FIG. 10 shows an enlarged view of a portion of the third region 60c. In FIG. 10, the fourth focus detection pixels 302SNL and 302SNR and the fifth focus detection pixels 302LNL and 302LNR are represented by the characters "SNL," "SNR," "LNL," and "LNR," respectively. The third region 60c has a total of five types of focus detection pixel arrays 61: focus detection pixel array 61N, focus detection pixel array 61S, focus detection pixel array 61L, focus detection pixel array 61SN, and focus detection pixel array 61LN.

[0049] In the focus detection pixel column 61SN, fourth focus detection pixels 302SNL and 302SNR are alternately arranged at regular intervals d in the left-right direction (X-axis direction). In the focus detection pixel column 61LN, fifth focus detection pixels 302LNL and 302LNR are alternately arranged at regular intervals d in the left-right direction (X-axis direction). That is, in the third region 60c, some of the imaging and focus detection pixels 301 have been replaced with first focus detection pixels 302NL and 302NR, second focus detection pixels 302SL and 302SR, third focus detection pixels 302LL and 302LR, fourth focus detection pixels 302SNL and 302SNR, and fifth focus detection pixels 302LNL and 302LNR.

[0050] Next, we will explain the focus detection process performed by the first focus detection unit 221 and the second focus detection unit 222. At the start of the focus detection process, one focus detection area is set in advance on the shooting screen. The focus detection area may be set manually by the user using an operating member such as a button (not shown), or it may be set automatically by the body CPU 220 using well-known main subject recognition processing such as face recognition.

[0051] In focus detection processing, first, the second focus detection unit 222 performs focus detection calculation in the focus detection area based on focus detection signals output from the focus detection pixels 302. This focus detection calculation is more suitable for detecting large defocus, that is, a state where the image is significantly out of focus, than the focus detection calculation performed by the first focus detection unit 221 (details will be described later). Therefore, in the following description, the focus detection calculation performed by the second focus detection unit 222 will be referred to as the focus detection calculation for large defocus.

[0052] When the second focus detection unit 222 detects a defocus amount equal to or greater than a predetermined amount, i.e., when a large defocus is detected, the focus adjustment unit 230 drives the focusing lens 112 based on the detection result. On the other hand, when the second focus detection unit 222 detects a defocus amount less than the predetermined amount, i.e., when the imaging optical system 110 is in focus to a certain extent, the first focus detection unit 221 performs a focus detection calculation in the focus detection area based on the focus detection signals output from the imaging and focus detection pixels 301. The focus adjustment unit 230 then drives the focusing lens 112 based on the detection result. Here, the focus detection calculation performed by the first focus detection unit 221 is more suitable for focus detection when the defocus is not large than the focus detection calculation performed by the second focus detection unit 222 (details will be described later). Therefore, in the following description, the focus detection calculation performed by the first focus detection unit 221 will be referred to as a focus detection calculation for small defocus.

[0053] The following describes the focus detection calculation for large defocus performed by the second focus detection unit 222. The second focus detection unit 222 first selects a focus detection pixel row 61 from near the focus detection area that corresponds to the position of the exit pupil of the imaging optical system 110. For example, if the focus detection area is near the center of the shooting screen and only the focus detection pixel row 61N is present in that vicinity, then that focus detection pixel row 61N will inevitably be selected.

[0054] On the other hand, if the focus detection area is located away from the center of the shooting screen and three focus detection pixel rows 61L, 61N, and 61S are present nearby, one of these focus detection pixel rows 61 is selected depending on the position of the exit pupil of the imaging optical system 110. Specifically, if the exit pupil of the imaging optical system 110 is located relatively far (farther than a predetermined distance), the focus detection pixel row 61L is selected. Conversely, if the exit pupil of the imaging optical system 110 is located relatively close (close within a predetermined distance), the focus detection pixel row 61S is selected. If neither of these is the case (located somewhere in between), the focus detection pixel row 61N is selected.

[0055] Next, the second focus detection unit 222 acquires focus detection signals from focus detection pixels in the selected focus detection pixel row 61. For example, if the focus detection pixel row 61N is selected, the first focus detection pixels 302NL and 302NR are arranged in a row within that focus detection pixel row 61N. The second focus detection unit 222 generates a pair of focus detection signals: an output signal obtained by arranging the outputs of the many first focus detection pixels 302NL (light-receiving outputs of the photoelectric conversion unit 34), and an output signal obtained by arranging the outputs of the many first focus detection pixels 302NR (light-receiving outputs of the photoelectric conversion unit 34). Then, a correlation calculation is performed to calculate the phase difference between the pair of focus detection signals, and the defocus amount is calculated. Since this type of calculation is well known, a description thereof will be omitted.

[0056] The focus detection calculation performed by the second focus detection unit 222 is suitable for focus detection during large defocus because the photoelectric conversion unit 34 of the focus detection pixel 302 is partially shielded from light by the light-shielding member 35. When the imaging optical system 110 is significantly out of focus (i.e., when the defocus amount is very large), the focus detection signal obtained from the imaging and focus detection pixel 301 becomes a gradual signal with unclear contrast. It is difficult to accurately detect the phase difference of such a signal using correlation calculation.

[0057] In contrast, the photoelectric conversion unit 34 of the focus detection pixel 302 has incident light restricted by the light-shielding member 35, and the width in the focus detection direction (X-axis direction) of the range into which the light beam that has passed through the imaging optical system 110 is incident is smaller than the width in the same direction of the photoelectric conversion units 34L and 34R of the imaging and focus detection pixel 301.

[0058] Generally, when the aperture 130 of the imaging optical system 110 is set to a small aperture, the depth of field becomes deeper and a subject image with less blur is obtained, and a similar effect can be achieved with the focus detection pixel 302. In other words, even when the imaging optical system 110 is significantly out of focus (i.e., when the defocus amount is very large), the focus detection signal obtained from the focus detection pixel 302 will have higher contrast (a sharper contrast, more accurately representing the original subject image) than the focus detection signal obtained from the imaging and focus detection pixel 301. With such a signal, phase difference detection by correlation calculation is easier to perform than with the focus detection signal obtained from the imaging and focus detection pixel 301. Therefore, even when the focus is significantly out of focus, more accurate focus detection calculation can be performed than with the imaging and focus detection pixel 301.

[0059] As described above, the second focus detection unit 222 selects an appropriate focus detection pixel array 61 depending on the position of the exit pupil of the imaging optical system 110, preventing the light beam from the exit pupil from being blocked, which would interfere with focus detection. In the first region 60a, even if the exit pupil of the imaging optical system 110 is far away, the angle of incidence of the light beam from the exit pupil in the X-axis direction is not as large as in the second region 60b or the third region 60c. Therefore, the light beam from the exit pupil is not blocked by the focus detection pixel array 61N, and the focus detection pixel array 61N alone is sufficient. Therefore, only the focus detection pixel array 61N is arranged in the first region 60a. The number of focus detection pixel types arranged in the second region 60b is smaller than in the third region 60c for the same reason.

[0060] Next, the focus detection calculation for small defocus performed by the first focus detection unit 221 will be described. The first focus detection unit 221 first acquires focus detection signals from imaging and focus detection pixels 301 near the focus detection area. For example, it selects a large number of imaging and focus detection pixels 301 arranged in a horizontal row near the focus detection area. It then generates a pair of focus detection signals, consisting of an output signal obtained by arranging the light-receiving outputs of the photoelectric conversion units 34L of the selected imaging and focus detection pixels 301 and an output signal obtained by arranging the light-receiving outputs of the photoelectric conversion units 34R of the selected imaging and focus detection pixels 301. The first focus detection unit 221 performs a correlation calculation to calculate the phase difference between the pair of focus detection signals and then calculates the defocus amount. Since this type of calculation is well known, a description thereof will be omitted.

[0061] Unlike the photoelectric conversion unit 34 of the focus detection pixel 302, the photoelectric conversion units 34L and 34R of the imaging and focus detection pixel 301 do not limit the amount of incident light. Therefore, the amount of light photoelectrically converted is greater than that of the focus detection pixel 302. In other words, the signal amount of the focus detection signal is greater than that of the focus detection pixel 302. Therefore, when the defocus amount is relatively small, the defocus amount obtained by the focus detection calculation performed by the second focus detection unit 222 is more accurate than the defocus amount obtained by the focus detection calculation performed by the first focus detection unit 221. Therefore, in this embodiment, when the defocus amount is small, focus adjustment is performed based on the result of focus detection by the first focus detection unit 221.

[0062] 11 is a flowchart of the control process executed by the body CPU 220. When the camera body 200 is powered on, the body CPU 220 reads a control program including this control process from the ROM 240 and begins execution.

[0063] First, in step S10, the body CPU 220 begins cyclic operation of the image sensor 210, that is, begins reading out image signals at predetermined intervals (for example, 1 / 60th of a second) to create a live view image. In step S20, the body CPU 220 determines whether a predetermined autofocus adjustment operation (for example, half-pressing the release switch) has been performed. If no autofocus adjustment operation has been performed, the body CPU 220 proceeds to step S30.

[0064] In step S30, the body CPU 220 reads out imaging signals for creating a live view image from the imaging and focus detection pixels of the image sensor 210. The imaging signals read out here are signals for creating a live view image, and it is not necessary to read signals from all imaging and focus detection pixels. For example, thinning readout is performed, in which every third pixel is read out. In step S40, the body CPU 220 updates the live view image displayed on the display device 250. That is, a live view image is created using the imaging signals read out in step S30 and displayed on the display device 250. The body CPU 220 then proceeds to step S20.

[0065] On the other hand, if an autofocus operation has not been performed in step S20, the body CPU 220 proceeds to step S50. In step S50, the body CPU 220 executes autofocus (AF) processing, which will be described later. In step S60, the body CPU 220 determines whether a predetermined release operation (for example, a full press of the release switch) has been performed. If a release operation has not been performed, the body CPU 220 proceeds to step S70.

[0066] In step S70, the body CPU 220 reads out imaging signals for creating a live view image from the imaging and focus detection pixels of the image sensor 210. In step S80, the body CPU 220 updates the live view image displayed on the display device 250. That is, a live view image is created using the imaging signals read out in step S70 and displayed on the display device 250. The body CPU 220 then proceeds to step S20.

[0067] On the other hand, if a release operation has been performed in step S60, the body CPU 220 proceeds to step S90. In step S90, the body CPU 220 reads out image signals from the imaging and focus detection pixels 301 of the image sensor 210. The image signals read out here are signals of recorded image data (main image data). Since it is desirable for the recorded image data to have as high an image quality as possible, signals are read out from all of the imaging and focus detection pixels 301. In step S100, the body CPU 220 interpolates the focus detection pixels 302. That is, since no image signal is obtained from the position where the focus detection pixel 302 is located, the image signal that would normally be obtained from that position (if there were an imaging and focus detection pixel 301 at that position) is artificially generated based on image signals obtained from the surrounding imaging and focus detection pixels 301.

[0068] In step S110, the body CPU 220 creates recording image data and stores it on a storage medium (e.g., a memory card, etc.) not shown. In step S120, the body CPU 220 determines whether a predetermined power-off operation (e.g., pressing the power switch) has been performed. If the power-off operation has not been performed, the body CPU 220 proceeds to step S20. On the other hand, if the power-off operation has been performed, the body CPU 220 ends the processing of FIG. 11.

[0069] Figure 12 is a flowchart of the AF processing called in step S30 of Figure 11. First, in step S200, the second focus detection unit 222 selects one focus detection pixel row from the focus detection pixel rows near the focus detection area based on current information about the imaging optical system 110 (such as the exit pupil position). For example, if the focus detection area is located in the third region 60c and the exit pupil of the imaging optical system 110 is somewhat far away, focus detection pixel row 61L is selected. Note that the current information about the imaging optical system 110 can be received by the body CPU 220 from the lens CPU 120 via data communication between the lens CPU 120 and the body CPU 220.

[0070] In step S210, the second focus detection unit 222 reads out focus detection signals from the focus detection pixels 302 included in the focus detection pixel row selected in step S200. In step S220, the second focus detection unit 222 performs focus detection calculations based on the focus detection signals read out in step S210, i.e., focus detection calculations for large defocus.

[0071] In step S230, the second focus detection unit 222 determines whether a defocus amount equal to or greater than a predetermined amount, i.e., large defocus, was detected by the focus detection calculation for large defocus performed in step S220. If a defocus amount equal to or greater than the predetermined amount was detected, the second focus detection unit 222 proceeds to step S240. In step S240, the focus adjustment unit 230 drives the focusing lens 112 based on the defocus amount obtained by the focus detection calculation for large defocus. Thereafter, the second focus detection unit 222 proceeds to step S200.

[0072] On the other hand, if a defocus amount equal to or greater than the predetermined amount is not detected in step S230 (for example, if the detected defocus amount is less than the predetermined amount or if the defocus amount cannot be detected), the second focus detection unit 222 proceeds to step S250. In step S250, the first focus detection unit 221 reads out a light reception signal (light reception output) from the imaging and focus detection pixel 301. As described above, the signal read out here can be treated as both an imaging signal and a focus detection signal.

[0073] In step S260, the body CPU 220 updates the live view image being displayed on the display device 250. That is, it treats the signal read out in step S250 as an imaging signal, creates a live view image, and displays it on the display device 250. In step S270, the first focus detection unit 221 selects one pixel row made up of imaging and focus detection pixels 301 lined up in the focus detection direction (X-axis direction) from near the focus detection area. In step S280, the first focus detection unit 221 uses the signal read out in step S250 that corresponds to the pixel row selected in step S270 as a focus detection signal, and performs focus detection calculation based on that focus detection signal, i.e., focus detection calculation for small defocus.

[0074] In step S290, the body CPU 220 determines whether the focus detection calculation for small defocus performed in step S280 was successful. If phase difference detection cannot be performed due to reasons such as low contrast of the subject image and focus detection fails, the body CPU 220 proceeds to step S300. In step S300, the body CPU 220 determines whether the most recent focus detection calculation for large defocus performed in step S220 was successful. If the calculation of the defocus amount by the most recent focus detection calculation for large defocus was successful, the body CPU 220 proceeds to step S310.

[0075] In step S310, the focus adjustment unit 230 drives the focusing lens 112 based on the defocus amount obtained by the focus detection calculation for large defocus. After that, the body CPU 220 advances the process to step S200.

[0076] In step S300, if the most recent focus detection calculation for large defocus failed to calculate the defocus amount, the body CPU 220 proceeds to step S320. In step S320, the focus adjustment unit 230 performs so-called search driving (scan driving), which moves the focusing lens over a certain range. Thereafter, the body CPU 220 proceeds to step S200.

[0077] If, in step S290, the focus detection calculation for small defocus performed in step S280 was successful, the body CPU 220 proceeds to step S330. In step S330, the body CPU 220 determines whether the imaging optical system 110 is in focus, that is, whether the defocus amount detected in step S280 is sufficiently small (smaller than a predetermined threshold). If the imaging optical system 110 is not in focus, that is, if the defocus amount is equal to or greater than the predetermined threshold, the body CPU 220 proceeds to step S340. In step S340, the focus adjustment unit 230 drives the focusing lens 112 based on the defocus amount obtained by the focus detection calculation for small defocus. The body CPU 220 then proceeds to step S250. Note that the reason processing proceeds to step S250 rather than step S200 here is because it is clear that the image is already in focus to a certain extent (not in a large defocus state). If the focus is achieved in step S330, that is, if the defocus amount is smaller than the predetermined threshold, the body CPU 220 ends the AF processing. As described above, in the AF processing of this embodiment, first, focus detection calculation for large defocus is performed, and if a large defocus state is detected, focus detection calculation for small defocus, which is likely to fail, is not performed, and lens driving is performed based on the result of the focus detection calculation for large defocus.

[0078] According to the camera system of the first embodiment described above, the following advantageous effects can be obtained. (1) The image sensor 210 is arranged with a plurality of imaging and focus detection pixels 301 into which incident light enters a predetermined range, and a plurality of types of focus detection pixels 302 into which incident light enters a range smaller than that of the imaging and focus detection pixels 301. The image sensor 210 has a first region 60a in which one type of focus detection pixel 302 is arranged, and a second region 60b which has a higher image height than the first region 60a and in which more types of focus detection pixels 302 are arranged than in the first region 60a. This allows appropriate focus detection to be performed in both large and small defocus states.

[0079] (2) The width of the aperture of the multiple types of focus detection pixels 302 in a predetermined direction is smaller than that of the imaging and focus detection pixel 301. This allows appropriate focus detection to be performed in both a large defocus state and a small defocus state.

[0080] (3) The first focus detection pixels 302NR, 302NL corresponding to the first exit pupil position are arranged in the first region 60a, and the first focus detection pixels 302NR, 302NL and the second focus detection pixels 302SR, 302SL corresponding to a second exit pupil position different from the first exit pupil position are arranged in the second region 60b. As a result, appropriate focus detection can be performed even if the exit pupil position changes, for example, because the interchangeable lens 100 is replaced with a different type of lens.

[0081] (4) The distance in the X-axis direction from the optical axis of the imaging optical system 110 (the center of the imaging surface 20) to the first region 60a is shorter than the distance in the same direction from the optical axis of the imaging optical system 110 (the center of the imaging surface 20) to the second region 60b. This makes it possible to arrange only the minimum number of focus detection pixels 302 in positions where subject light is unlikely to be blocked, improving the image quality of the captured image data.

[0082] (5) The image sensor 210 has an imaging / focus detection pixel 301 into which incident light enters a predetermined range, first focus detection pixels 302NR, NL into which incident light enters a range smaller than that of the imaging / focus detection pixel 301 and which correspond to a first exit pupil position, and second focus detection pixels 302SR, SL into which incident light enters a range smaller than that of the imaging / focus detection pixel 301 and which correspond to a second exit pupil position different from the first exit pupil position. The image sensor 210 has a first region 60a in which the first focus detection pixels 302NR, NL are arranged, and a second region 60b, which has a higher image height than that of the first region 60a and in which the first focus detection pixels 302NR, NL and second focus detection pixels 302SR, SL are arranged. This configuration makes it easier to manufacture the image sensor 210 than when two photoelectric conversion units 34 are provided for a single focus detection pixel 302.

[0083] (6) The image sensor 210 has a first focus detection pixel 302NR and a second focus detection pixel 302SR that receive light from one of a pair of exit pupils, and a first focus detection pixel 302NL and a second focus detection pixel 302SL that receive light from the other of the pair of exit pupils. This eliminates the need to individually modify the photoelectric conversion units 34, reducing the manufacturing costs of the image sensor 210.

[0084] (7) The image sensor 210 further includes third focus detection pixels LR and LL, which receive incident light over a smaller area than the imaging and focus detection pixels 301, and a third region 60c, which has a higher image height than the second region 60b and in which the first focus detection pixels 302NR and NL, the second focus detection pixels 302SR and SL, and the third focus detection pixels 302LR and LL are located. This configuration enables more precise focus detection to be performed according to the exit pupil position.

[0085] (8) A plurality of each of the plurality of types of focus detection pixels 302 is arranged along the X-axis direction. This allows focus detection using a phase difference detection method.

[0086] (9) The first focus detection unit 221 performs focus detection based on the focus detection signal output from the imaging and focus detection pixel 301. The second focus detection unit 222 performs focus detection based on the focus detection signal (photoelectric conversion signal) output from the first focus detection pixels 302NR and 302NL when the exit pupil of the imaging optical system 110 is at a first position, and performs focus detection based on the focus detection signal output from the second focus detection pixels 302SR and 302SL when the exit pupil of the imaging optical system 110 is at a second position. As a result, appropriate focus detection can always be performed regardless of whether the state is small or large defocus, or whether the exit pupil of the imaging optical system 110 is at the first or second position.

[0087] (10) If the result of focus detection by the second focus detection unit 222 indicates a predetermined amount of defocus or more, the focus adjustment unit 230 performs focus adjustment of the imaging optical system 110 based on the result of focus detection, and if the result of focus detection by the second focus detection unit 222 does not indicate a predetermined amount of defocus or more, the focus adjustment unit 230 performs focus adjustment of the imaging optical system 110 based on the result of focus detection by the first focus detection unit 221. As a result, there is no need to operate the first focus detection unit 221 in a large defocus state, which reduces the processing load on the body CPU 220 and reduces power consumption.

[0088] (Second embodiment) The camera system according to the second embodiment has the same configuration as the camera system according to the first embodiment, but the content of the AF processing executed by the body CPU 220 differs from that of the first embodiment. The AF processing in the second embodiment will be explained below.

[0089] Fig. 13 is a flowchart of the AF process called from step S50 in Fig. 11 in this embodiment. First, in step S400, the first focus detection unit 221 reads out a light reception signal (light reception output) from the imaging and focus detection pixel 301. As described above, the signal read out here can be treated as both an imaging signal and a focus detection signal.

[0090] In step S410, the body CPU 220 updates the live view image being displayed on the display device 250. That is, the signal read out in step S400 is treated as an imaging signal, and a live view image is created and displayed on the display device 250.

[0091] In step S415, the first focus detection unit 221 selects one pixel row made up of imaging and focus detection pixels 301 lined up in the focus detection direction (X-axis direction) from near the focus detection area. In step S420, the first focus detection unit 221 uses the signal read out in step S400 that corresponds to the pixel row selected in step S415 as a focus detection signal and performs focus detection calculation based on that focus detection signal, i.e., focus detection calculation for small defocus.

[0092] In step S430, the body CPU 220 determines whether the focus detection calculation for small defocus performed in step S420 was successful. If phase difference detection cannot be performed and focus detection fails, for example, because the imaging optical system 110 is significantly out of focus, i.e., in a large defocus state, the body CPU 220 proceeds to step S440.

[0093] In step S440, the second focus detection unit 222 selects one focus detection pixel row from those in the vicinity of the focus detection area based on current information (such as the exit pupil position) of the imaging optical system 110. In step S450, the second focus detection unit 222 reads out focus detection signals from the focus detection pixels 302 included in the focus detection pixel row selected in step S440. In step S460, the second focus detection unit 222 performs focus detection calculation based on the focus detection signal read out in step S450, i.e., focus detection calculation for large defocus.

[0094] In step S470, the body CPU 220 determines whether the focus detection calculation for large defocus performed in step S460 was successful. If focus detection failed, the body CPU 220 proceeds to step S490. In step S490, the focus adjustment unit 230 performs so-called search driving (scan driving), which moves the focusing lens over a certain range. Thereafter, the body CPU 220 proceeds to step S400.

[0095] On the other hand, if the calculation of the defocus amount by the focus detection calculation for large defocus was successful in step S470, the body CPU 220 proceeds to step S480. In step S480, the focus adjustment unit 230 drives the focusing lens 112 based on the defocus amount obtained by the focus detection calculation for large defocus. After that, the body CPU 220 proceeds to step S400.

[0096] If the calculation of the defocus amount by the focus detection calculation for small defocus was successful in step S430, the body CPU 220 proceeds to step S500. In step S500, the body CPU 220 determines whether the imaging optical system 110 is in focus, i.e., whether the defocus amount detected in step S420 is sufficiently small (smaller than a predetermined threshold). If the imaging optical system 110 is not in focus, i.e., if the defocus amount is equal to or greater than the predetermined threshold, the body CPU 220 proceeds to step S510. In step S510, the focus adjustment unit 230 drives the focusing lens 112 based on the defocus amount obtained by the focus detection calculation for small defocus. The body CPU 220 then proceeds to step S400. On the other hand, if the imaging optical system 110 is in focus in step S500, i.e., if the defocus amount is smaller than the predetermined threshold, the body CPU 220 ends the processing shown in FIG. 13. As described above, in the AF processing of this embodiment, first, focus detection calculation for small defocus is performed, and only if this fails, focus detection calculation for large defocus is performed.

[0097] According to the camera system of the second embodiment described above, the following advantageous effects can be obtained. (1) If focus detection by the first focus detection unit 221 is successful, the focus adjustment unit 230 adjusts the focus of the imaging optical system 110 based on the result of the focus detection, and if focus detection by the first focus detection unit 221 is unsuccessful, the focus adjustment unit 230 adjusts the focus of the imaging optical system 110 based on the result of the focus detection by the second focus detection unit 222. As a result, focus detection by the second focus detection unit 222 is performed only when there is a large amount of defocus, which reduces the processing load on the body CPU 220 and reduces power consumption.

[0098] (Third embodiment) The camera system according to the third embodiment has the same configuration as the camera system according to the first embodiment, but differs from the first embodiment in that it has an image sensor 210a with a different structure instead of image sensor 210. Image sensor 210a in the third embodiment will be described below.

[0099] 14 is a perspective view schematically showing the structure of an image sensor 210a according to the third embodiment. The image sensor 210a has a microlens array 211 and a photoelectric conversion array 212. The microlens array 211 has a plurality of microlenses 31 arranged in a two-dimensional square. The photoelectric conversion array 212 has a plurality of photoelectric conversion units 34 arranged in a two-dimensional square. Note that the arrangement of the plurality of microlenses 31 does not have to be a square array.

[0100] The microlens array 211 is disposed at a position spaced apart from the light receiving surface of the photoelectric conversion array 212 by the focal length f of the microlens 31. In other words, the microlens array 211 and the photoelectric conversion array 212 are disposed so that the focal position of the microlens 31 and the light receiving surface of the photoelectric conversion array 212 coincide with each other.

[0101] In this embodiment, the diameter of one microlens 31 is larger than the width of one photoelectric conversion unit 34. In other words, one microlens 31 covers multiple photoelectric conversion units 34. Subject light that passes through one microlens 31 is incident on multiple photoelectric conversion units 34 corresponding to that microlens 31. As illustrated in FIG. 14 , multiple photoelectric conversion units 34 are included in range 215 where light that passes through one microlens 31 is incident.

[0102] The image sensor 210a has a plurality of pixels 30. The pixels 30 include two types of pixels: imaging and focus detection pixels 301 that are used for both imaging and focus detection, and focus detection pixels 302 that are used only for focus detection. These two types of pixels will be described below.

[0103] FIG. 15 is a cross-sectional view schematically illustrating an imaging / focus detection pixel 301 and a focus detection pixel 302. Note that FIG. 15 schematically illustrates a cross-section of the central portion of the imaging surface of the image sensor 210a. In the first embodiment, one pixel 30 had one microlens 31. In contrast, in the present embodiment, a plurality of pixels 30 share one microlens 31. In other words, in the present embodiment, the microlens 31 owned by one pixel 30 and the microlens 31 owned by another pixel 30 may be the same microlens 31.

[0104] The imaging and focus detection pixel 301 has a microlens 31, a color filter 32, and a photoelectric conversion unit 34. Light incident on the microlens 31 is incident on the photoelectric conversion unit 34 via the color filter 32. The color filter 32 is formed so that it transmits either red, blue, or green light for each pixel and blocks other light. The color filter 32 of the imaging and focus detection pixel 301 is configured in a so-called Bayer array. The imaging and focus detection pixel 301 outputs the photoelectric conversion signal output by the photoelectric conversion unit 34.

[0105] 3(c) , the imaging and focus detection pixels 301 according to this embodiment, like the imaging and focus detection pixels 301 according to the first embodiment, are farther away from the center of the imaging surface than the optical axis 41 of the microlens 31 and the center of the photoelectric conversion unit 34, and the distance between them increases as the distance from the center of the imaging surface increases. This is the same as in the first embodiment, so illustrations and explanations will be omitted.

[0106] The focus detection pixel 302 is similar to that of the first embodiment, except that the microlens 31 is shared among multiple pixels 30. That is, the focus detection pixel 302 has a microlens 31, a color filter 32, a photoelectric conversion unit 34, and a light blocking member 35. Incident light that enters the microlens 31 passes through the color filter 32, and a portion of the light that is not blocked by the light blocking member 35 enters the photoelectric conversion unit 34.

[0107] In this embodiment, as in the first embodiment, the focus detection pixels 302 include many types of focus detection pixels: first focus detection pixels 302NL and 302NR, second focus detection pixels 302SL and 302SR, third focus detection pixels 302LL and 302LR, fourth focus detection pixels 302SNL and 302SNR, and fifth focus detection pixels 302LNL and 302LNR. In the first embodiment, these focus detection pixels differed in that they had different aperture widths, but in this embodiment, the aperture widths are all the same.

[0108] Fig. 16 is an enlarged plan view of a portion of the first region 60a (Fig. 7) of the image sensor 210a. In Fig. 16, the letters "R", "G", and "B" represent imaging pixels 303 having red, green, and blue color filters 32, respectively, and the letters "NL" and "NR" represent first focus detection pixels 302NL and 302NR, respectively.

[0109] In the first embodiment, the first focus detection pixels 302NL and 302NR were arranged alternately at regular intervals d in the left-right direction (X-axis direction) in the focus detection pixel row 61N in the first region 60a. In the present embodiment, instead of the focus detection pixel row 61N, a microlens row 610N is considered in which microlenses 31, each including a focus detection pixel 302, are arranged in a row in the left-right direction (X-axis direction). The first focus detection pixels 302NL and 302NR are arranged alternately in the microlenses 31 included in the microlens row 610N in the first region 60a at regular intervals (every other microlens in FIG. 16 ).

[0110] For example, the 6 × 6 pixels 30 with the microlens 31a on the left side of Fig. 16 includes one first focus detection pixel 302NL, while the 6 × 6 pixels 30 with the microlens 31b to the right does not include a focus detection pixel 302. The 6 × 6 pixels 30 with the microlens 31c one microlens to the right also includes one first focus detection pixel 302NR.

[0111] A pair of first focus detection pixels 302NL and 302NR are arranged in each microlens 31 in point symmetry with respect to the chief ray from the expected exit pupil position. For example, in the microlens array 610N shown in FIG. 16, the position of the chief ray from the expected exit pupil position is indicated by the circle LP. When focusing on each microlens 31, the first focus detection pixel 302NL and the first focus detection pixel 302NR are arranged in point symmetry with respect to the circle LP. Specifically, the first focus detection pixel 302NL is arranged immediately to the lower right of the circle LP, and the first focus detection pixel 302NR is arranged immediately to the upper left of the circle LP.

[0112] Figure 17 is an enlarged plan view of a portion of the second region 60b (Figure 7) of the image sensor 210a. In Figure 17, the second focus detection pixels 302SL, 302SR and the third focus detection pixels 302LL, 302LR are represented by the letters "SL," "SR," "LL," and "LR," respectively. Three types of microlens arrays 61 are provided in the second region 60b: microlens array 610L, microlens array 610N, and microlens array 610S, each of which has multiple microlens arrays.

[0113] First focus detection pixels 302NL and 302NR are alternately arranged at regular intervals (every other pixel in FIG. 17) on the microlenses 31 included in the microlens row 610N. Second focus detection pixels 302SL and 302SR are alternately arranged at regular intervals (every other pixel in FIG. 17) on the microlenses 31 included in the microlens row 610S. Third focus detection pixels 302LL and 302LR are alternately arranged at regular intervals (every other pixel in FIG. 17) on the microlenses 31 included in the microlens row 610L.

[0114] The pair of second focus detection pixels 302SL and 302SR and the pair of third focus detection pixels 302LL and 302LR are arranged in each microlens 31 in point symmetry with respect to the chief ray from the expected exit pupil position. For example, in the microlens array 610S shown in FIG. 17, the position of the chief ray from the expected exit pupil position is indicated by the circle LP. When focusing on each microlens 31, the second focus detection pixel 302SL and the second focus detection pixel 302SR are arranged in point symmetry with respect to the circle LP. Specifically, the second focus detection pixel 302SL is arranged immediately below and to the right of the circle LP, and the second focus detection pixel 302SR is arranged immediately above and to the left of the circle LP. The same is true for the third focus detection pixels 302LL and 302LR.

[0115] The first focus detection pixels 302NL and 302NR are disposed near the optical axis of the microlens 31. In contrast, the second focus detection pixels 302SL and 302SR are disposed at a fixed distance to the right of the page from the optical axis of the microlens 31. Similarly, the third focus detection pixels 302LL and 302LR are disposed at a fixed distance to the left of the page (the opposite direction from the second focus detection pixels 302SL and 302SR) from the optical axis of the microlens 31.

[0116] As described above, in this embodiment, the positions of the focus detection pixels 302 vary depending on the assumed pupil position. That is, the focus detection pixels 302 are positioned according to the assumed pupil position. For example, light from the exit pupil position assumed by the first focus detection pixels 302NL and 302NR forms a spot near the center of the microlens 31, so the first focus detection pixels 302NL and 302NR are positioned near the center of the microlens 31. On the other hand, the second focus detection pixels 302SL and 302SR, which assume a short pupil position, form a spot on the side closer to the optical axis of the image sensor 210a with respect to the optical axis of the microlens 31, i.e., on the left side in FIG. 16 , so the second focus detection pixels 302SL and 302SR are positioned to the right of the optical axis of the microlens 31. The opposite is true for the third focus detection pixels 302LL and 302LR, which are positioned to the left of the optical axis of the microlens 31.

[0117] Figure 18 is an enlarged plan view of a portion of the third region 60c (Figure 7) of the image sensor 210a. In Figure 18, the fourth focus detection pixels 302SNL and 302SNR and the fifth focus detection pixels 302LNL and 302LNR are represented by the characters "SNL," "SNR," "LNL," and "LNR," respectively. Within the third region 60c, multiple microlens rows 610 are provided, each of five types: microlens row 610S, microlens row 610SN, microlens row 610N, microlens row 610LN, and microlens row 610L.

[0118] In the microlenses 31 included in the microlens column 610N, first focus detection pixels 302NL and 302NR are alternately arranged at regular intervals (every other pixel in FIG. 18). In the microlenses 31 included in the microlens column 610S, second focus detection pixels 302SL and 302SR are alternately arranged at regular intervals (every other pixel in FIG. 18). In the microlenses 31 included in the microlens column 610L, third focus detection pixels 302LL and 302LR are alternately arranged at regular intervals (every other pixel in FIG. 18). In the microlenses 31 included in the microlens column 610SN, fourth focus detection pixels 302SNL and 302SNR are alternately arranged at regular intervals (every other pixel in FIG. 18). In the microlenses 31 included in the microlens column 610LN, fifth focus detection pixels 302LNL and 302LNR are alternately arranged at regular intervals (every other pixel in FIG. 18).

[0119] The pair of fourth focus detection pixels 302SNL and 302SNR and the pair of fifth focus detection pixels 302LNL and 302LNR are arranged point-symmetrically with respect to the chief ray from the expected exit pupil position within each microlens 31. For example, in the microlens array 610SN shown in FIG. 18, the position of the chief ray from the expected exit pupil position is indicated by the circle LP. When focusing on each microlens 31, the fourth focus detection pixel 302SNL and the fourth focus detection pixel 302SNR are arranged point-symmetrically with respect to the circle LP. Specifically, the fourth focus detection pixel 302SNL is arranged immediately below and to the right of the circle LP, and the fourth focus detection pixel 302SNR is arranged immediately above and to the left of the circle LP. The same is true for the fifth focus detection pixels 302LNL and 302LNR.

[0120] The fourth focus detection pixels 302SNL and 302SNR are located at a fixed distance to the right of the page from the optical axis of the microlens 31. The distance from the optical axis of the microlens 31 is shorter than that of the second focus detection pixels 302SL and 302SR. Similarly, the fifth focus detection pixels 302LNL and 302LNR are located at a fixed distance to the left of the page (the opposite direction from that of the fourth focus detection pixels 302SNL and 302SNR) from the optical axis of the microlens 31. The distance from the optical axis of the microlens 31 is shorter than that of the third focus detection pixels 302LL and 302LR.

[0121] The image sensor 210a configured as described above can be used to realize a so-called refocusing function, which synthesizes an image of an arbitrary image plane (a so-called refocused image) within a predetermined range in the optical axis direction from the image pickup signals output by the image pickup and focus detection pixels 301. The refocusing function will be described below.

[0122] FIG. 19 is a cross-sectional view schematically showing a light beam from a light point P on an image plane S to be combined and the image sensor 210a. In FIG. 19, consider a light point P provided on the image plane S to be combined. The spread angle θ of light from this light point P toward the image sensor 12 is determined by the size of the pupil of the imaging optical system 110 (i.e., the aperture value of the imaging optical system 110). The aperture value of the microlens 31 is configured to be the same as or smaller than the aperture value of the imaging optical system 110. Therefore, the light beam emitted from this light point P and incident on a certain microlens 31 does not spread outside the area covered by that microlens 31.

[0123] 19, if a light beam from a light point P is incident on five microlenses 31(1) to 31(5), the total amount of incident light limited to the pupil from the light point P can be obtained by integrating the amount of light incident on the light receiving surface of light beams 300(1) to 300(5) that are incident on these microlenses 31(1) to 31(5) (the photoelectric conversion outputs of photoelectric conversion units 34(1) to 34(5)). In other words, the amount of light from the light point P (the pixel to be synthesized) on the image plane S to be synthesized can be obtained.

[0124] The body CPU 220 sets multiple light points P on the specified image plane S, and for each light point P, identifies the microlens 31 onto which the light flux from that light point P is incident. For each identified microlens 31, the body CPU 220 identifies which photoelectric conversion unit 34 the light flux from that light point P is incident on. The body CPU 220 calculates the pixel value of the light point P by integrating the photoelectric conversion output of the identified photoelectric conversion unit 34. Note that if the identified photoelectric conversion unit 34 is the photoelectric conversion unit 34 of the focus detection pixel 302, it is desirable to use, instead of the photoelectric conversion output from that photoelectric conversion unit 34, the photoelectric conversion output obtained by performing an interpolation operation based on the photoelectric conversion outputs of the surrounding photoelectric conversion units 34.

[0125] Through the above processing, images of the image plane S designated as the composition target are composited. The body CPU 220 can composite images of multiple different image planes for the imaging signal output from the imaging element 210a by one imaging operation. In other words, images of multiple image planes can be obtained from the result of one imaging operation.

[0126] However, there are certain restrictions on the position of the image plane that can be suitably combined while maintaining a certain resolution through the above processing. For example, it is known that combining image planes near the vertices of the microlenses 31 results in a lower resolution than combining image planes at other positions. Thus, there are restrictions on the position of the image plane that can be combined. Therefore, the body CPU 220 recognizes main subjects included in the imaging range using well-known subject recognition technology, etc., and drives the focusing lens 112 so that these main subjects are included in a range that can be suitably combined (hereinafter simply referred to as the compositeable range). Focus adjustment in this embodiment refers to adjusting the position of the focusing lens 112 so that the main subjects are included in the compositeable range.

[0127] Next, the focus detection calculation for small defocus performed by the first focus detection unit 221 will be described. The first focus detection unit 221 first acquires focus detection signals from the imaging and focus detection pixels 301 near the focus detection area. For example, it selects a number of microlenses 31 arranged in a horizontal row near the focus detection area. Then, for each of the selected microlenses 31, it generates a signal by adding together the light-receiving outputs of the photoelectric conversion units 34 of the imaging and focus detection pixels 301 located in the left half of the microlens 31 and a signal by adding together the light-receiving outputs of the photoelectric conversion units 34 of the imaging and focus detection pixels 301 located in the right half of the microlens 31. This pair of signals can be treated as a pair of focus detection signals, similar to the light-receiving outputs of the photoelectric conversion units 34L and 34R in the first embodiment. The first focus detection unit 221 performs a correlation calculation to calculate the phase difference between the pair of focus detection signals and then calculates the defocus amount. Since this calculation is well known, a detailed description will be omitted.

[0128] In the above explanation, the light receiving outputs of the photoelectric conversion units 34 of the imaging and focus detection pixels 301 arranged on the left and right halves of the microlens 31 are added together. However, by reducing the number of photoelectric conversion units 34 used for the addition, it is possible to obtain a focus detection signal that appears as if the amount of incident light is limited. The fewer the number of photoelectric conversion units 34 used for the addition, the better the system can handle large defocus, but the signal amount of the focus detection signal decreases and the accuracy decreases. Therefore, for example, when the defocus is small, it is desirable to add the light receiving outputs from many photoelectric conversion units 34. On the other hand, it is also possible to handle large defocus by generating a pair of focus detection signals using only the light receiving outputs from two (pairs of) photoelectric conversion units 34.

[0129] Furthermore, in the case of large defocus, focus detection may not be possible even with a pair of focus detection signals using only the received light outputs from two (a pair of) photoelectric conversion units 34. In such a case, in this embodiment, focus adjustment is performed using the result of focus detection calculation for large defocus performed by the second focus detection unit 222.

[0130] Next, we will explain the focus detection calculation for large defocus performed by the second focus detection unit 222. The second focus detection unit 222 first selects a microlens array 610 from the vicinity of the focus detection area according to the position of the exit pupil of the imaging optical system 110. For example, if the focus detection area is near the center of the shooting screen and only the microlens array 610N is present in that vicinity, then that microlens array 610N will inevitably be selected.

[0131] On the other hand, if the focus detection area is located away from the center of the shooting screen and three microlens arrays 610S, 610N, and 610L are present nearby, one of the microlens arrays 610 is selected according to the position of the exit pupil of the imaging optical system 110. Specifically, if the exit pupil of the imaging optical system 110 is located relatively far away (farther than a predetermined distance), the microlens array 610L is selected. Conversely, if the exit pupil of the imaging optical system 110 is located relatively close (close within a predetermined distance), the microlens array 610S is selected. If neither of these is the case (located in an intermediate position), the microlens array 610N is selected.

[0132] Next, the second focus detection unit 222 acquires focus detection signals from the focus detection pixels 302 in the selected microlens row 610. For example, if the microlens row 610N is selected, the first focus detection pixels 302NL and 302NR are arranged in a row within that microlens row 610N. The second focus detection unit 222 generates a pair of focus detection signals, consisting of an output signal obtained by arranging the outputs of the many first focus detection pixels 302NL (light-receiving outputs of the photoelectric conversion unit 34) and an output signal obtained by arranging the outputs of the many first focus detection pixels 302NR (light-receiving outputs of the photoelectric conversion unit 34). Then, a correlation calculation is performed to calculate the phase difference between the pair of focus detection signals, and the defocus amount is calculated. Since this type of calculation is well known, a description thereof will be omitted.

[0133] The pair of focus detection signals obtained here are focus detection signals that can handle even larger defocus than the pair of focus detection signals that use only the received light outputs from the two (pair) photoelectric conversion units 34 described above, because the aperture is limited by the light-shielding member 35.

[0134] According to the camera system of the third embodiment described above, the following advantageous effects can be obtained. (1) A focus detection pixel 302 and multiple imaging and focus detection pixels 301 onto which light that has passed through a certain microlens 31 is incident, and a focus detection pixel 302 and multiple imaging and focus detection pixels 301 onto which light that has passed through another microlens 31 is incident, are provided. This configuration enables appropriate focus detection even in a so-called refocus camera, regardless of whether the defocus state is large or small.

[0135] The following modifications are also within the scope of the present invention, and one or more of the modifications may be combined with the above-described embodiment.

[0136] (Variation 1) In the above-described embodiment, the light blocking member 35 having an opening of a predetermined width is provided in the focus detection pixel 302. In this way, instead of providing the light blocking member 35, the width of the photoelectric conversion unit 34 may actually be reduced.

[0137] FIG. 20(a) illustrates a first focus detection pixel 302NR' that has a photoelectric conversion unit 34NR formed to match the position and size of the opening 36NR instead of the light blocking member 35 having the opening 36NR.

[0138] The first focus detection pixels 302NR and 302NL may be a single pixel having a pair of photoelectric conversion units. That is, for one pixel, a photoelectric conversion unit 34 with a size corresponding to the opening 36NR may be provided at a position corresponding to the opening 36NR, and another photoelectric conversion unit 34 with a size corresponding to the opening 36NL may be provided at a position corresponding to the opening 36NL, replacing the first focus detection pixels 302NR and 302NL in the above-described embodiment. The same applies to the second to fifth focus detection pixels.

[0139] Alternatively, a single pixel may be provided with a pair of photoelectric conversion units 34L, 34R similar to the imaging and focus detection pixel 301, and may also be provided with both openings 36NL, 36NR in the light blocking member 35. The same applies to the second to fifth focus detection pixels.

[0140] (Variation 3) If a light blocking member 35 is provided in the focus detection pixel 302, there is a possibility that light beams that do not enter the photoelectric conversion unit 34 (light beams that enter the light blocking member 35) may leak into the adjacent imaging and focus detection pixel 301. To prevent such stray light, an anti-reflection film may be provided on the surface of the light blocking member 35. FIG. 20(b) shows an example of a first focus detection pixel 302NR'' in which an anti-reflection film 37 is provided on the surface of the light blocking member 35.

[0141] (Variation 4) The number of types, number of locations, and arrangement of the focus detection pixels 302 may differ from those in the above-described embodiment. Similarly, the number of types, number of locations, shapes, and arrangement pattern of the regions in which the focus detection pixels 302 are arranged, exemplified as the first region 60a, the second region 60b, and the third region 60c, may differ from those in the above-described embodiment.

[0142] 21(a) shows an example in which the first region 60a, the second region 60b, and the third region 60c are arranged in an arc shape. Also, FIG. 21(b) shows an example in which the first region 60a, the second region 60b, and the third region 60c are arranged in a concentric circle shape. As such, various shapes and arrangement patterns of the regions in which the focus detection pixels 302 are arranged are possible.

[0143] (Variation 5) The shape of the pair of photoelectric conversion units 34R, 34L included in the imaging and focus detection pixel 301 may be different from that shown in FIG. 3(a). For example, as shown in FIG. 22(a), they may be rectangular. The focus detection direction is not limited to the X-axis direction, but may be, for example, the Y-axis direction. In this case, a pair of photoelectric conversion units 34T, 34B may be provided that are separated in the Y-axis direction, as shown in FIG. 22(b), for example.

[0144] Furthermore, both the X-axis and Y-axis directions can be used as focus detection directions. For example, as shown in FIG. 22(c), four photoelectric conversion units 34a, 34b, 34c, and 34d are provided. In this case, adding the light reception signals of the two photoelectric conversion units 34a and 34c located on the left side of the page results in a signal equivalent to the light reception signal of the photoelectric conversion unit 34L shown in FIG. 22(a). Adding the light reception signals of the two photoelectric conversion units 34a and 34b located on the upper side of the page results in a signal equivalent to the light reception signal of the photoelectric conversion unit 34T shown in FIG. 22(b). Therefore, if the imaging and focus detection pixel 301 is configured as shown in FIG. 22(c) and a focus detection pixel 302 is provided having photoelectric conversion units with smaller widths in the X-axis and Y-axis directions than the four photoelectric conversion units 34a, 34b, 34c, and 34d, both the X-axis and Y-axis directions become focus detection directions.

[0145] The present invention is not limited to the above-described embodiments, and other forms that are conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention, as long as the features of the present invention are not impaired. [Explanation of symbols]

[0146] 1... camera system, 100... interchangeable lens, 110... imaging optical system, 112... focusing lens, 120... lens CPU, 130... aperture, 200... camera body, 210... image sensor, 220... body CPU, 221... first focus detection unit, 222... second focus detection unit, 230... focus adjustment unit, 240... ROM, 250... display device, 301, 301a, 301b... image capture and focus detection pixels, 302... focus detection pixel

Claims

1. a plurality of first pixel columns that receive light transmitted through the imaging optical system and output signals used for focus detection, and that have a plurality of first pixels arranged along a first direction; a plurality of second pixel columns that receive light transmitted through the imaging optical system and output signals used for focus detection, the second pixel columns having a plurality of second pixels arranged along the first direction; a plurality of third pixels that receive light transmitted through the imaging optical system and output signals used for imaging; a circuit for selecting one of the first pixel row and the second pixel row based on information about an exit pupil position of the imaging optical system; An imaging element comprising: the first pixel receives light through an opening provided at a first position of the light-shielding portion; the second pixel receives light through an opening provided at a second position of the light-shielding portion that is different from the first position; the imaging element includes: a first region in which either one of the plurality of first pixel columns and the plurality of second pixel columns and the third pixel are arranged; and a second region having the same size as the first region, a higher image height in the first direction than the first region, and in which both the plurality of first pixel columns and the plurality of second pixel columns and the third pixel are arranged. Image sensor.

2. the circuit selects either the first pixel row or the second pixel row based on information relating to a position of a focus detection area on an imaging plane and an exit pupil position of the imaging optical system. The imaging device according to claim 1 .

3. the first pixel includes a pair of pixels that respectively receive a pair of pupil-split light beams, the second pixel includes a pair of pixels that respectively receive a pair of pupil-divided light beams; 3. The imaging device according to claim 1.

4. the circuit selects the first pixel row when an exit pupil position of the imaging optical system is at a first exit pupil position, and selects the second pixel row when the exit pupil position of the imaging optical system is at a second exit pupil position different from the first exit pupil position. The imaging device according to claim 1 .

5. the first region is a region including the center of the imaging surface; The imaging device according to claim 1 .

6. In the second region, the second pixel row is spaced apart from the first pixel row in a second direction perpendicular to the first direction. The imaging device according to claim 1 .

7. The second region has the same image height as the first region in a second direction perpendicular to the first direction. The imaging device according to claim 1 .

8. an image sensor including: a plurality of first pixel rows each having a plurality of first pixels arranged along a first direction, each receiving light transmitted through an imaging optical system and outputting a signal used for focus detection; a plurality of second pixel rows each having a plurality of second pixels arranged along the first direction, each receiving light transmitted through the imaging optical system and outputting a signal used for focus detection; and a plurality of third pixels each receiving light transmitted through the imaging optical system and outputting a signal used for imaging; a detection unit that selects one of the first pixel row and the second pixel row based on information about an exit pupil position of the imaging optical system, and detects a defocus amount using a signal from the selected pixel row; An imaging device comprising: the first pixel receives light through an opening provided at a first position of the light-shielding portion; the second pixel receives light through an opening provided at a second position of the light-shielding portion that is different from the first position; the imaging device includes: a first region in which either one of the plurality of first pixel columns and the plurality of second pixel columns and the third pixel are arranged; and a second region having the same size as the first region, a higher image height in the first direction than the first region, and in which both the plurality of first pixel columns and the plurality of second pixel columns and the third pixel are arranged. Imaging device.

9. the detection unit selects one of the first pixel row and the second pixel row based on information relating to a position of a focus detection area on an imaging plane and an exit pupil position of the imaging optical system. The imaging device according to claim 8 .

10. the first pixel includes a pair of pixels that respectively receive a pair of pupil-split light beams, the second pixel includes a pair of pixels that respectively receive a pair of pupil-divided light beams; 10. The imaging device according to claim 8 or claim 9.

11. the detection unit selects the first pixel row when an exit pupil position of the imaging optical system is at a first exit pupil position, and selects the second pixel row when the exit pupil position of the imaging optical system is at a second exit pupil position different from the first exit pupil position. The imaging device according to any one of claims 8 to 10.

12. the first region is a region including the center of the imaging surface; The imaging device according to any one of claims 8 to 11.

13. In the second region, the second pixel row is spaced apart from the first pixel row in a second direction perpendicular to the first direction. The imaging device according to any one of claims 8 to 12.

14. The second region has the same image height as the first region in a second direction perpendicular to the first direction. The imaging device according to any one of claims 8 to 13.

Images