Imaging element and imaging apparatus

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 apparatus. [Background technology]

[0002] There has been known an image sensor that has focus detection pixels on the imaging surface for performing focus detection using a pupil division method. Conventionally, there has been a problem that focus detection is difficult when the image is significantly out of focus (large defocus). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-106994 A Summary of the Invention

[0004] According to a first aspect, an image sensor includes a plurality of first pixel rows having a plurality of first pixels that receive light transmitted through an imaging optical system and output a signal used for focus detection, a plurality of second pixel rows having a plurality of second pixels that receive light transmitted through the imaging optical system and output a signal used for focus detection, and a circuit that selects one of the first pixel rows and the second pixel rows based on information regarding an exit pupil position of the imaging optical system, wherein the first pixels receive light through an opening provided at a first position of a light-shielding portion, and the second pixels receive light through an opening provided at a second position different from the first position of the light-shielding portion, and includes a first region in which only one of the plurality of first pixel rows and the plurality of second pixel rows is arranged, and a second region having a higher image height than the first region and in which both the plurality of first pixel rows and the plurality of second pixel rows are arranged. According to a second aspect, an imaging device includes an imaging element including a plurality of first pixel rows having a plurality of first pixels that receive light transmitted through an imaging optical system and output a signal used for focus detection, and a plurality of second pixel rows having a plurality of second pixels that receive light transmitted through the imaging optical system and output a signal used for focus detection, and a detection unit that selects one of the first pixel rows or the second pixel rows based on information regarding an exit pupil position of the imaging optical system and detects a defocus amount using a signal from the selected pixel row, wherein the first pixels receive light through an opening provided at a first position of a light-shielding unit, and the second pixels receive light through an opening provided at a second position different from the first position of the light-shielding unit, and includes a first region in which only one of the plurality of first pixel rows and the plurality of second pixel rows is arranged, and a second region having a higher image height than the first region and in which both the plurality of first pixel rows and the plurality of second pixel rows are arranged. [Brief description of the drawings]

[0005] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of a camera system according to a first embodiment of the present invention. [Diagram 2] 2 is a plan view showing a schematic diagram of an imaging surface 20 of an imaging element 210. FIG. [Diagram 3] FIG. 3 is an explanatory diagram of an imaging and focus detection pixel 301. [Figure 4] 3 is an explanatory diagram of first focus detection pixels 302NR and 302NL. FIG. [Diagram 5] 3 is an explanatory diagram of second focus detection pixels 302SR and 302SL. FIG. [Figure 6] 13 is an explanatory diagram of third focus detection pixels 302LR and 302LL. FIG. [Figure 7] 2 is a plan view showing a schematic diagram of an imaging surface 20 of an imaging element 210. FIG. [Figure 8] 1 is an enlarged view of a portion of the first region 60a. [Figure 9] 13 is an enlarged view of a portion of the second region 60b. [Figure 10] 13 is an enlarged view of a portion of the third region 60c. [Figure 11] 13 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] 2 is a perspective view showing a schematic structure of an imaging element 210a. [Figure 15] 3 is a cross-sectional view showing a schematic diagram of an imaging / focus detection pixel 301 and a focus detection pixel 302. FIG. [Figure 16] 1 is an enlarged plan view of a portion of a first region 60a of an image sensor 210a. [Figure 17] 13 is an enlarged plan view of a portion of the second region 60b of the image sensor 210a. [Figure 18] 13 is an enlarged plan view of a portion of the inside of a third region 60c of the image sensor 210a. [Figure 19] 1 is a cross-sectional view showing a schematic diagram of a light beam from a light point P on an image plane S to be synthesized and an image sensor 210a. [Figure 20] 13 is an explanatory diagram of a first focus detection pixel according to a modified example. FIG. [Figure 21] 13 is an explanatory diagram of an imaging surface according to a modified example. FIG. [Figure 22] 10A and 10B are explanatory diagrams of imaging and focus detection pixels according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 the components particularly related to the present invention, and omits other components constituting the camera system 1. The following description will focus on the components particularly related to the present invention, and omits description of the 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 a plurality of 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. One of the plurality of types of interchangeable lenses 100 is shown as an example in FIG. 1.

[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 a mount portion of the interchangeable lens 100 into a 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 composed of a lens 111 and a focusing lens 112. The imaging optical system 110 forms a subject image on an 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 imaging element 210, a body CPU 220, a focus adjustment unit 230, a ROM 240, and a display device 250. The imaging element 210 is, for example, an imaging element such as a CCD or CMOS. The imaging element 210 receives subject light that has passed through the imaging optical system 110, and outputs an imaging 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 reads and executes a control program prestored in a ROM 240, which is 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 based on the control of the body CPU 220. The display device 250 is, for example, a display device such as a liquid crystal display, and displays a live view image, various setting screens, and the like.

[0011] The body CPU 220 is provided with a first focus detection section 221 and a second focus detection section 222 in the form of software. These sections 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 section 221 detects the focus adjustment state of the imaging optical system 110 based on focus detection signals output from imaging and focus detection pixels described later. The second focus detection section 222 detects the focus adjustment state of the imaging optical system 110 based on focus detection signals output from focus detection pixels described later.

[0013] (Explanation of the imaging element 210) Fig. 2(a) is a plan view showing a schematic diagram of the imaging surface 20 of the imaging element 210. For ease of explanation, a coordinate system is set in Fig. 2(a) 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 rear 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 set for the subsequent drawings.

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

[0015] As shown in Fig. 2(b), a large number of pixels 30 are two-dimensionally arranged in a 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 in Fig. 2(b) there is no distinction between the two. Below, the imaging and focus detection pixels 301 will be described, focusing in particular on the imaging and focus detection pixel 301a located in the center of the imaging surface 20 (the intersection of the vertical line OX and the horizontal line OY).

[0016] FIG. 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 has 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 have an approximately semicircular shape obtained by dividing a circle along the Y-axis direction. That is, the pair of photoelectric conversion units 34L and 34R are arranged along the X-axis direction (focus detection direction). The width of the pair of photoelectric conversion units 34L and 34R in the X-axis direction is at most W1.

[0017] The microlens 31 focuses the incident light on the imaging and focus detection pixel 301a onto a pair of photoelectric conversion units 34L and 34R. The 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 any one of red, blue, and green light for each pixel and not transmit other light. The color filter 32 of the imaging and focus detection pixel 301a is configured to form 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 a portion between the pixels so as not to block the incident light to 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). Also, 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 outputs the photoelectric conversion signal output by the photoelectric conversion unit 34L and the photoelectric conversion signal output by the photoelectric conversion unit 34R separately. A signal obtained by adding up the pair of photoelectric conversion signals is substantially the same as an 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 a phase difference between a signal consisting 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 consisting of the photoelectric conversion signals output by the photoelectric conversion units 34L of the 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 a focus detection signal capable of performing focus detection calculation using a well-known phase difference method.

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

[0022] Next, the imaging and focus detection pixel 301b (see FIG. 2(b)), which is four pixels away from the imaging and focus detection pixel 301a in the right direction (+X direction) of the paper, will be described. 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 FIG. 3(b) and FIG. 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 position 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] In this way, in the imaging and focus detection pixel 301b located away from the center of the imaging surface 20, the position of the optical axis 41 of the microlens 31 is separated from the dividing line 42 of the pair of photoelectric conversion units 34L and 34R, and the distance 40 increases as the distance from the center of the imaging surface 20 increases. Since the light flux that has passed through the imaging optical system 110 is incident on the imaging and focus detection pixel 301b from the upper left direction to the lower right direction of the paper in FIG. 3(c), in order to improve light collection, the microlens 31 is disposed so as to be shifted by the distance 40 according to the angle of the incident light. Note that, although only the shift in the X-axis direction has been described in FIGS. 3(b) and 3(c), the position of the microlens 31 and the position of the pair of photoelectric conversion units 34L and 34R are similarly disposed so as to be different from each other in the Y-axis direction.

[0024] Next, the focus detection pixels 302 will be described. In addition to the imaging and focus detection pixels described above, the image sensor 210 has many types of focus detection pixels, including 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, and the structure of these focus detection pixels will be described below first.

[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 blocking member 35. The differences between the above-described imaging / 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 blocking 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 (called 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, and 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 differs from that of the opening 36NR.

[0028] The openings 36NR and 36NL are located on the left and right of the dashed-dotted line 44N. In other words, the dashed-dotted line 44N is a straight line that defines the division center of the openings 36NR and 36NL. In the following description, the dashed-dotted line 44N is referred to as the division line 44N. The first focus detection pixel 302NR outputs a light receiving signal corresponding to the optical image of the subject formed on the right side of the division line 44N, and the first focus detection pixel 302NL outputs a light receiving signal corresponding to the optical image of the subject formed on the left side 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 in Figs. 3(a) to (c). That is, a more restricted light flux is incident on the photoelectric conversion units 34 of the first focus detection pixels 302NR, 302NL than on 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 focus is significantly off the subject portion to be focused, the focus detection signals output from the first focus detection pixels 302NR, 302NL have a 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 signals 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, it may be said that "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 and 34L in the focus detection direction (X-axis direction)" to indicate that the width of the openings 36NR and 36NL in the focus detection direction is smaller than the width of the photoelectric conversion units 34R and 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 refers to the width of the incidence range of incident light to the photoelectric conversion unit 34, so that "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 and 34L in the focus detection direction (X-axis direction)" includes the case where the photoelectric conversion unit 34 is actually formed to have a small width, and the case where the light shielding member 35 or the like is provided so that the incidence range of light incident on the photoelectric conversion unit 34 has a small width.

[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 that passes through the vertex of the microlens 31, among the chief rays of the exit pupil of the imaging optical system 110. 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, 302NL.

[0032] Fig. 5(a) is a cross-sectional view of the second focus detection pixel 302SR, and Fig. 5(b) is a cross-sectional view of the second focus detection pixel 302SL. The second focus detection pixels 302SR, 302SL have almost the same configuration as the first focus detection pixels 302NR, 302NL shown in Figs. 4(a) and 4(b), respectively, and differ from the first focus detection pixels 302NR, 302NL in that openings 36SR, 36SL are provided in the light blocking member 35 instead of openings 36NR, 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 on the left and right sides of the two-dot chain line 44S. In other words, the two-dot chain line 44S is a straight line that determines the division center of the openings 36SR and 36SL. In the following description, the two-dot chain line 44S will be referred to as the division 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 divides the photoelectric conversion unit 34 in half in the left-right direction (X-axis direction) on the page.

[0035] 5(a) and (b) show a chief ray 43S that passes through the apex of the microlens 31 among the chief rays of the exit pupil of the imaging optical system 110. 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 FIG. 4(a) and (b). That is, even if the exit pupil of the imaging optical system 110 is located relatively close and the subject light is not incident on the openings 36NR and 36NL of the first focus detection pixels 302NR and 302NL, the subject light is incident on 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, whereas the opening 36SR is located at a second position different from the first position.

[0036] Fig. 6(a) is a cross-sectional view of the third focus detection pixel 302LR, and Fig. 6(b) is a cross-sectional view of the third focus detection pixel 302LL. The third focus detection pixels 302LR, 302LL have almost the same configuration as the first focus detection pixels 302NR, 302NL shown in Fig. 4(a) and (b), respectively, and differ from the first focus detection pixels 302NR, 302NL in that openings 36LR, 36LL are provided in the light blocking member 35 instead of openings 36NR, 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 determines the division center of the openings 36LR and 36LL. In the following description, the two-dot chain line 44L will be referred to as the division 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 divides the photoelectric conversion unit 34 in half in the left-right direction (X-axis direction) on the page.

[0039] 6(a) and (b) show a chief ray 43S that passes through the apex of the microlens 31 among the chief rays of the exit pupil of the imaging optical system 110. 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 (b). That is, even if the exit pupil of the imaging optical system 110 is located relatively far away and subject light is not incident on the openings 36NR and 36NL of the first focus detection pixels 302NR and 302NL, subject light is incident on 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 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 position assumed by the first focus detection pixels 302NL and 302NR and closer than the position assumed by the third focus detection pixels 302LL and 302LR, the focus detection signal can be suitably output. The fifth focus detection pixels 302LNL, 302LNR correspond to the first focus detection pixels 302NL, 302NR, respectively, and the division center of the opening provided in the light blocking member 35 exists between the division line 44N of the first focus detection pixels 302NL, 302NR and the division line 44S of the second focus detection pixels 302SL, 302SR. In other words, when the exit pupil of the imaging optical system 110 is closer than the assumed position of the first focus detection pixels 302NL, 302NR and farther than the assumed position of the second focus detection pixels 302SL, 302SR, the focus detection signal can be suitably output.

[0041] As described above, the image sensor 210 has five types of focus detection pixels (first focus detection pixels 302NL, 302NR, second focus detection pixels 302SL, 302SR, third focus detection pixels 302LL, 302LR, fourth focus detection pixels 302SNL, 302SNR, fifth focus detection pixels 302LNL, 302LNR), and these five types of focus detection pixels have different assumed exit pupil positions. In other words, they correspond to different imaging optical systems 110. The position of the exit pupil changes, for example, when the interchangeable lens 100 is replaced with a different type of lens, or when the zoom position is changed in a so-called zoom lens with a variable focal length. 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 that shows a schematic diagram of the imaging surface 20 (i.e., the photographing screen) of the image sensor 210. Consider five regions obtained by dividing the imaging surface 20 into five equal parts in the left-right direction. Each of the regions has a rectangular shape with its long side parallel to the vertical line OX. Of the 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 ends of the imaging surface 20 are defined as a third region 60c. In this embodiment, a plurality of 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 in the first region 60a, the second region 60b, and the 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 the imaging and focus detection pixels 301 having red, green, and blue color filters 32, respectively, and the letters "NL" and "NR" represent the first focus detection pixels 302NL and 302NR, respectively.

[0045] 8, in the focus detection pixel row 61N in the first region 60a, the first focus detection pixels 302NL, 302NR are alternately arranged at a constant interval d along the left-right direction (X-axis direction). For example, the pixels 30 are arranged from left to right as follows: the first focus detection pixel 302NL, a plurality of imaging and focus detection pixels 301a, the first focus detection pixel 302NR, a plurality of imaging and focus detection pixels 301a, the 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 rows 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 characters "SL", "SR", "LL", and "LR", respectively. The second region 60b has three types of focus detection pixel rows 61: a focus detection pixel row 61N, a focus detection pixel row 61S, and a focus detection pixel row 61L, each of which has a plurality of rows.

[0047] In the focus detection pixel row 61N, the first focus detection pixels 302NL, 302NR are alternately arranged at a constant interval d in the left-right direction (X-axis direction). In the focus detection pixel row 61S, the second focus detection pixels 302SL, 302SR are alternately arranged at a constant interval d in the left-right direction (X-axis direction). In the focus detection pixel row 61L, the third focus detection pixels 302LL, 302LR are alternately arranged at a constant interval d in the left-right direction (X-axis direction). That is, in the second region 60b, some of the imaging and focus detection pixels 301 are replaced with the first focus detection pixels 302NL, 302NR, the second focus detection pixels 302SL, 302SR, and the third focus detection pixels 302LL, 302LR.

[0048] As shown in Fig. 7, the third region 60c has more focus detection pixel rows 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, 302SNR, and the fifth focus detection pixels 302LNL, 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 rows 61, namely, a focus detection pixel row 61N, a focus detection pixel row 61S, a focus detection pixel row 61L, a focus detection pixel row 61SN, and a focus detection pixel row 61LN, each of which has a plurality of focus detection pixel rows 61.

[0049] In the focus detection pixel row 61SN, the fourth focus detection pixels 302SNL and 302SNR are alternately arranged at a constant interval d in the left-right direction (X-axis direction). In the focus detection pixel row 61LN, the fifth focus detection pixels 302LNL and 302LNR are alternately arranged at a constant interval 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 are replaced with the first focus detection pixels 302NL and 302NR, the second focus detection pixels 302SL and 302SR, the third focus detection pixels 302LL and 302LR, the fourth focus detection pixels 302SNL and 302SNR, and the fifth focus detection pixels 302LNL and 302LNR.

[0050] Next, a description will be given of the focus detection process by the first focus detection section 221 and the second focus detection section 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 may be set automatically by the body CPU 220 using a well-known main subject recognition process such as face recognition.

[0051] In the focus detection process, first, the second focus detection unit 222 performs a focus detection calculation in the focus detection area based on the focus detection signals output from the focus detection pixels 302. This focus detection calculation is more suitable for detecting a large defocus, that is, a state where the focus 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 a 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, that is, 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 a defocus amount less than a predetermined amount is detected, that is, when the imaging optical system 110 is in focus to a certain extent, the first focus detection unit 221 performs a focus detection calculation based on a focus detection signal output from the imaging and focus detection pixel 301 in the focus detection area. Then, the focus adjustment unit 230 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 compared to 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 is 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 that corresponds to the position of the exit pupil of the imaging optical system 110 from the vicinity of the focus detection area. 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 the 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 there are three focus detection pixel rows 61L, 61N, and 61S in the vicinity, one of them 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 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 in an intermediate position), the focus detection pixel row 61N is selected.

[0055] Next, the second focus detection section 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 in the focus detection pixel row 61N. The second focus detection section 222 generates a pair of focus detection signals, which are an output signal obtained by arranging the outputs (receiving light outputs of the photoelectric conversion section 34) of a large number of first focus detection pixels 302NL and an output signal obtained by arranging the outputs (receiving light outputs of the photoelectric conversion section 34) of a large number of first focus detection pixels 302NR. 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 such calculations are 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. The focus detection signal obtained from the imaging and focus detection pixel 301 becomes a gradual signal with unclear contrast when the imaging optical system 110 is significantly out of focus (i.e. when the defocus amount is very large). It is difficult to accurately detect the phase difference of such a signal by correlation calculation.

[0057] In contrast, the photoelectric conversion unit 34 of the focus detection pixel 302 has incident light restricted by a 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, 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 deep and a subject image with a small amount of blur is obtained, and the focus detection pixel 302 also has a similar effect. That is, even if the imaging optical system 110 is significantly out of focus (i.e., the amount of defocus is very large), the focus detection signal obtained from the focus detection pixel 302 becomes a signal with higher contrast (steeper, 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, it is easier to perform phase difference detection by correlation calculation compared to the focus detection signal obtained from the imaging and focus detection pixel 301. Therefore, even if 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 row 61 according to the position of the exit pupil of the imaging optical system 110, so that the light beam from the exit pupil is not blocked, which causes problems in focus detection. In the first region 60a, even if the exit pupil of the imaging optical system 110 is far away, the incident angle of the light beam from the exit pupil in the X-axis direction is not so large compared to the second region 60b and the third region 60c, so that the light beam from the exit pupil is not blocked even by the focus detection pixel row 61N, and the focus detection pixel row 61N alone is sufficient. Therefore, only the focus detection pixel row 61N is arranged in the first region 60a. The number of types of focus detection pixels arranged in the second region 60b is smaller than that 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 the imaging and focus detection pixels 301 in the vicinity of the focus detection area. For example, a large number of imaging and focus detection pixels 301 arranged in a horizontal row in the vicinity of the focus detection area are selected. Then, a pair of signals, 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, are set as a pair of focus detection signals. The first focus detection unit 221 performs a correlation calculation to calculate the phase difference of the pair of focus detection signals, and calculates the defocus amount. Since such calculation is well known, a description thereof will be omitted.

[0061] The photoelectric conversion units 34L and 34R of the imaging and focus detection pixel 301 do not limit the amount of incident light, unlike the photoelectric conversion unit 34 of the focus detection pixel 302. Therefore, the amount of light photoelectrically converted is larger than that of the focus detection pixel 302. That is, the signal amount of the focus detection signal is larger than that of the focus detection pixel 302. Therefore, when the defocus amount is relatively small, the defocus amount obtained by the second focus detection unit 222 through the focus detection calculation is more accurate than the defocus amount obtained by the first focus detection unit 221 through the focus detection calculation. Therefore, in this embodiment, when the defocus 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 power of the camera body 200 is turned 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 starts the periodic operation of the image sensor 210, that is, reading out the image signal at a predetermined time interval (for example, 1 / 60th of a second) for creating a live view image. In step S20, the body CPU 220 determines whether or not a predetermined autofocus adjustment operation (for example, pressing the release switch halfway) has been performed. If an autofocus adjustment operation has not been performed, the body CPU 220 advances the process 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 advances the process to step S20.

[0065] On the other hand, if an automatic focus adjustment operation has not been performed in step S20, the body CPU 220 advances the process to step S50. In step S50, the body CPU 220 executes automatic focus adjustment (AF) processing, which will be described later. In step S60, the body CPU 220 determines whether or not 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 advances the process 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 advances the process to step S20.

[0067] On the other hand, if a release operation has been performed in step S60, the body CPU 220 advances the process to step S90. In step S90, the body CPU 220 reads out imaging signals from the imaging and focus detection pixels 301 of the image sensor 210. The imaging 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 imaging signal is obtained from the position where the focus detection pixel 302 exists, an imaging signal that would normally be obtained from that position (if there was an imaging and focus detection pixel 301 at that position) is artificially generated based on imaging signals obtained from the surrounding imaging and focus detection pixels 301.

[0068] In step S110, the body CPU 220 creates record image data and stores it in a storage medium (e.g., a memory card, etc.) not shown. In step S120, the body CPU 220 determines whether or not 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 advances the process to step S20. On the other hand, if the power-off operation has been performed, the body CPU 220 ends the process of FIG.

[0069] Fig. 12 is a flowchart of the AF process called from step S30 in Fig. 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 (e.g., the exit pupil position, etc.). For example, when 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, the focus detection pixel row 61L is selected. Note that the body CPU 220 may receive information about the current imaging optical system 110 from the lens CPU 120 through data communication between the lens CPU 120 and the body CPU 220.

[0070] In step S210, the second focus detection section 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 section 222 performs focus detection calculation based on the focus detection signals read out in step S210, i.e., focus detection calculation for large defocus.

[0071] In step S230, the second focus detection unit 222 determines whether or not a defocus amount equal to or greater than a predetermined amount, i.e., large defocus, has been 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 has been detected, the second focus detection unit 222 advances the process 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. After that, the second focus detection unit 222 advances the process 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 (if the detected defocus amount is less than the predetermined amount, or if the defocus amount cannot be detected, etc.), the second focus detection unit 222 advances the process to step S250. In step S250, the first focus detection unit 221 reads out a light receiving signal (light receiving output) from the imaging and focus detection pixel 301. As described above, the signal read out here is a signal that 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 displayed on the display device 250. That is, the signal read out in step S250 is treated as an imaging signal, and a live view image is created and displayed 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 corresponding to the pixel row selected in step S270 from the signals read out in step S250 as a focus detection signal, and performs focus detection calculation based on that focus detection signal, that is, 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. For example, 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 advances processing 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 advances processing to step S310.

[0075] In step S310, the focus adjustment section 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 has failed to calculate the defocus amount, the body CPU 220 advances the process to step S320. In step S320, the focus adjustment unit 230 moves the focusing lens over a certain range, performing so-called search driving (scan driving). After that, the body CPU 220 advances the process to step S200.

[0077] In step S290, if the focus detection calculation for small defocus performed in step S280 was successful, the body CPU 220 advances the process to step S330. In step S330, the body CPU 220 judges 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 value). If the imaging optical system 110 is not in focus, that is, if the defocus amount is equal to or greater than a predetermined threshold value, the body CPU 220 advances the process 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. After that, the body CPU 220 advances the process to step S250. Note that the reason why the process advances to step S250 instead of 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 a predetermined threshold, the body CPU 220 ends the AF process. As described above, in the AF process 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 according to the above-described first embodiment, 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 is incident within a predetermined range, and a plurality of types of focus detection pixels 302 into which incident light is incident within 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 in which a greater number of types of focus detection pixels 302 are arranged than in the first region 60a and which has a higher image height than the first region 60a. As a result, appropriate focus detection can be performed in both a large defocus state and a small defocus state.

[0079] (2) The multiple types of focus detection pixels 302 have an aperture with a width in a predetermined direction that is smaller than that of the imaging / focus detection pixel 301. This makes it possible to perform appropriate focus detection in both a large defocus state and a small defocus state.

[0080] (3) First focus detection pixels 302NR, 302NL corresponding to a first exit pupil position are arranged in the first region 60a, and the first focus detection pixels 302NR, 302NL and 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, even if the position of the exit pupil changes due to, for example, replacing the interchangeable lens 100 with a different type of lens, appropriate focus detection can be performed.

[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 a minimum number of focus detection pixels 302 in positions where the 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 is incident in a predetermined range, first focus detection pixels 302NR, NL into which incident light is incident in 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 is incident in 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 having an image height higher than that of the first region 60a and in which the first focus detection pixels 302NR, NL and the second focus detection pixels 302SR, SL are arranged. This makes it easier to manufacture the image sensor 210 than when two photoelectric conversion units 34 are provided in 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, and reduces the manufacturing costs of the image sensor 210.

[0084] (7) The image sensor 210 further has third focus detection pixels LR and LL, into which incident light is incident in an area smaller than that of the imaging and focus detection pixel 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 arranged. This makes it possible to perform more precise focus detection according to the exit pupil position.

[0085] (8) The multiple types of focus detection pixels 302 are each arranged in multiple numbers along the X-axis direction. This makes it possible to perform 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 the 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 the 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) The focus adjustment unit 230 performs focus adjustment of the imaging optical system 110 based on the result of focus detection by the second focus detection unit 222 when the result of focus detection by the second focus detection unit 222 indicates a predetermined amount or more of defocus, and performs focus adjustment of the imaging optical system 110 based on the result of focus detection by the first focus detection unit 221 when the result of focus detection by the second focus detection unit 222 does not indicate a predetermined amount or more of defocus. As a result of this, there is no need to operate the first focus detection unit 221 in a large defocus state, and the processing load on the body CPU 220 is reduced, making it possible to reduce 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 contents of the AF processing executed by the body CPU 220 differ from those in 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 / 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, a live view image is created, and is displayed on the display device 250.

[0091] In step S415, the first focus detection unit 221 selects one pixel row consisting 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 corresponding to the pixel row selected in step S415 from the signals read out in step S400 as a focus detection signal, and performs focus detection calculation based on the focus detection signal, that is, 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 because the imaging optical system 110 is significantly out of focus, i.e., in a large defocus state, and focus detection has failed, the body CPU 220 advances processing 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 (e.g., 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 advances the process to step S490. In step S490, the focus adjustment unit 230 moves the focusing lens over a certain range, performing so-called search driving (scan driving). After that, the body CPU 220 advances the process to step S400.

[0095] On the other hand, if the calculation of the defocus amount by the focus detection calculation for large defocus is successful in step S470, the body CPU 220 advances the process 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 advances the process to step S400.

[0096] If the calculation of the defocus amount by the focus detection calculation for small defocus is successful in step S430, the body CPU 220 advances the process to step S500. In step S500, the body CPU 220 judges whether the imaging optical system 110 is in focus, that is, whether the defocus amount detected in step S420 is sufficiently small (smaller than a predetermined threshold value). 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 value, the body CPU 220 advances the process 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. After that, the body CPU 220 advances the process to step S400. On the other hand, if the imaging optical system 110 is in focus in step S500, that is, if the defocus amount is smaller than the predetermined threshold value, the body CPU 220 ends the process shown in FIG. 13. As described above, in the AF process 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 according to the second embodiment described above, the following advantageous effects can be obtained. (1) When 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 when 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 at large defocus, reducing the processing load on the body CPU 220 and enabling power consumption to be reduced.

[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 having a different structure instead of the image sensor 210. The image sensor 210a in the third embodiment will be described below.

[0099] 14 is a perspective view showing a schematic 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 two-dimensionally in a square shape. The photoelectric conversion array 212 has a plurality of photoelectric conversion units 34 arranged two-dimensionally in a square shape. 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 has passed through one microlens 31 is incident on multiple photoelectric conversion units 34 corresponding to that microlens 31. As illustrated in FIG. 14 , a range 215 into which light passing through one microlens 31 is incident includes multiple photoelectric conversion units 34.

[0102] The image sensor 210a has a plurality of pixels 30. The pixels 30 include two types of pixels: imaging / 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 showing a schematic diagram of an imaging / focus detection pixel 301 and a focus detection pixel 302. Fig. 15 shows a schematic diagram of a cross section of a central portion of an imaging surface of an image sensor 210a. In the first embodiment, one pixel 30 has 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 of one pixel 30 and the microlens 31 of 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 as to transmit any one of red, blue, and green light for each pixel and not transmit other light. The color filter 32 of the imaging and focus detection pixel 301 is configured to form 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) according to the first embodiment, the imaging and focus detection pixels 301 according to the present embodiment have a larger distance between the optical axis 41 of the microlens 31 and the center of the photoelectric conversion unit 34 when they are farther away from the center of the imaging surface, and the greater the distance from the center of the imaging surface, the greater the distance. This is the same as in the first embodiment, so illustration and description will be omitted.

[0106] The focus detection pixel 302 is similar to that of the first embodiment, except that the microlens 31 is shared between 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. A portion of the light incident on the microlens 31 passes through the color filter 32 and is not blocked by the light blocking member 35, and 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, namely, 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 differ in that they have different opening widths, but in this embodiment, the opening 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 the imaging pixels 303 having red, green, and blue color filters 32, respectively, and the letters "NL" and "NR" represent the first focus detection pixels 302NL and 302NR, respectively.

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

[0110] For example, the 6 × 6 pixels 30 having the microlens 31a on the left side of Fig. 16, out of a total of 36 pixels, includes one first focus detection pixel 302NL. The 6 × 6 pixels 30 having the microlens 31b to the right of that, out of a total of 36 pixels, does not include a focus detection pixel 302. The 6 × 6 pixels 30 having the microlens 31c one microlens to the right of that, out of a total of 36 pixels, includes one first focus detection pixel 302NR.

[0111] A pair of first focus detection pixels 302NL, 302NR are arranged in each microlens 31 in point symmetry with respect to the chief ray from the assumed exit pupil position. For example, in the microlens array 610N shown in FIG. 16, the position of the chief ray from the assumed exit pupil position is indicated by a 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] Fig. 17 is an enlarged plan view of a portion of the second region 60b (Fig. 7) of the image sensor 210a. In Fig. 17, the second focus detection pixels 302SL, 302SR and the third focus detection pixels 302LL, 302LR are represented by the characters "SL", "SR", "LL", and "LR", respectively. In the second region 60b, three types of microlens arrays 61, namely, microlens array 610L, microlens array 610N, and microlens array 610S, are provided in multiples.

[0113] In the microlenses 31 included in the microlens row 610N, first focus detection pixels 302NL, 302NR are alternately arranged at regular intervals (every other pixel in FIG. 17). In the microlenses 31 included in the microlens row 610S, second focus detection pixels 302SL, 302SR are alternately arranged at regular intervals (every other pixel in FIG. 17). In the microlenses 31 included in the microlens row 610L, third focus detection pixels 302LL, 302LR are alternately arranged at regular intervals (every other pixel in FIG. 17).

[0114] A pair of second focus detection pixels 302SL, 302SR and a pair of third focus detection pixels 302LL, 302LR are arranged in each microlens 31 in point symmetry with respect to the chief ray from the assumed exit pupil position. For example, in the microlens row 610S shown in FIG. 17, the position of the chief ray from the assumed exit pupil position is indicated by a 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, 302LR.

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

[0116] Thus, in this embodiment, the positions at which the focus detection pixels 302 are arranged vary depending on the assumed pupil position. That is, the focus detection pixels 302 are arranged at positions according to the assumed pupil position. For example, the 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 arranged 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, that is, on the left side of FIG. 16, so the second focus detection pixels 302SL and 302SR are arranged on the right side of the optical axis of the microlens 31. The third focus detection pixels 302LL and 302LR are arranged on the opposite side, that is, on the left side of the optical axis of the microlens 31.

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

[0118] In the microlenses 31 included in the microlens row 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 row 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 row 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 row 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 row 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 in each microlens 31 in point symmetry with respect to the chief ray from the assumed exit pupil position. For example, in the microlens row 610SN shown in FIG. 18, the position of the chief ray from the assumed exit pupil position is indicated by a circle LP. When focusing on each microlens 31, the fourth focus detection pixel 302SNL and the fourth focus detection pixel 302SNR are arranged in point symmetry 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 disposed 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 disposed at a fixed distance to the left of the page (the opposite direction to 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] By using the image sensor 210a configured as above, it is possible to realize a so-called refocus function that synthesizes an image of an arbitrary image plane (so-called refocus image) within a predetermined range in the optical axis direction from the image pickup signal output by the image pickup and focus detection pixel 301. The refocus function will be described below.

[0122] Fig. 19 is a cross-sectional view showing a schematic diagram of a light beam from a light point P on an image plane S to be synthesized and an image sensor 210a. In Fig. 19, a light point P is considered to be provided on the image plane S to be synthesized. A 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)-31(5), the total amount of incident light limited to the pupil from the light point P can be obtained by integrating the amounts of incident light on the light receiving surfaces of light beams 300(1)-300(5) incident on these microlenses 31(1)-31(5) (the photoelectric conversion outputs of photoelectric conversion units 34(1)-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 into 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 the 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, a photoelectric conversion output obtained by performing an interpolation calculation based on the photoelectric conversion outputs from the surrounding photoelectric conversion units 34.

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

[0126] However, there are certain restrictions on the position of the image plane that can be suitably combined while maintaining a certain resolution by the above processing. For example, it is known that when the image plane near the apex of the microlens 31 is combined, the resolution is lower than when the image plane at another position is combined. Thus, there are restrictions on the position of the image plane that can be combined. Therefore, the body CPU 220 recognizes the main subjects included in the imaging range by a well-known subject recognition technology or the like, and drives the focusing lens 112 so that the main subjects are included in a range where they can be suitably combined (hereinafter simply referred to as a composite possible range). The focus adjustment in this embodiment refers to adjusting the position of the focusing lens 112 so that the main subjects are included in the composite possible 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 in the vicinity of the focus detection area. For example, a large number of microlenses 31 arranged in a horizontal row in the vicinity of the focus detection area are selected. Then, for each of the selected microlenses 31, a signal obtained by adding the light receiving outputs of the photoelectric conversion units 34 of the imaging and focus detection pixels 301 arranged in the left half of the microlens 31 and a signal obtained by adding the light receiving outputs of the photoelectric conversion units 34 of the imaging and focus detection pixels 301 arranged in the right half of the microlens 31 are generated. 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 this pair of focus detection signals, and calculates the defocus amount. Since such calculations are well known, their explanation will be omitted.

[0128] In the above description, 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, but by reducing the number of photoelectric conversion units 34 used for the addition, it is possible to obtain a focus detection signal as if the amount of incident light was limited. The more the number of photoelectric conversion units 34 used for the addition is reduced, the better the response to large defocus, but on the other hand, the signal amount of the focus detection signal becomes smaller and the accuracy becomes poorer. 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 respond to 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, a description will be given of 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 row 610 according to the position of the exit pupil of the imaging optical system 110 from the vicinity of the focus detection area. For example, if the focus detection area is near the center of the shooting screen and only the microlens row 610N is present in that vicinity, then the microlens row 610N will necessarily be selected.

[0131] On the other hand, when the focus detection area is located away from the center of the shooting screen and the three microlens arrays 610S, 610N, and 610L are present in the vicinity, one of the microlens arrays 610 is selected according to the position of the exit pupil of the imaging optical system 110. Specifically, when 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, when the exit pupil of the imaging optical system 110 is located relatively close (close within a predetermined distance), the microlens array 610S is selected. When neither of these is the case (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 in the microlens row 610N. The second focus detection unit 222 generates a pair of focus detection signals, which is an output signal obtained by arranging the outputs of a large number of first focus detection pixels 302NL (light receiving outputs of the photoelectric conversion unit 34) and an output signal obtained by arranging the outputs of a large number of 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 such calculations are well known, a description thereof will be omitted.

[0133] The pair of focus detection signals obtained here have an aperture restricted by the light-shielding member 35, and are therefore focus detection signals that can accommodate 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.

[0134] According to the camera system according to the above-described third embodiment, the following advantageous effects can be obtained. (1) There is provided a focus detection pixel 302 and a plurality of 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 a plurality of imaging and focus detection pixels 301 onto which light that has passed through another microlens 31 is incident. This makes it possible to perform 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 embodiment described above, 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. 20A 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 pixel 302NR and the first focus detection pixel 302NL may be a single pixel having a pair of photoelectric conversion units. That is, for one pixel, a photoelectric conversion unit 34 having a size equivalent to the opening 36NR may be provided at a position equivalent to the opening 36NR, and another photoelectric conversion unit 34 having a size equivalent to the opening 36NL may be provided at a position equivalent to the opening 36NL, replacing the first focus detection pixels 302NR, NL in the above-mentioned embodiment. The same applies to the second to fifth focus detection pixels.

[0139] Alternatively, one pixel may be provided with a pair of photoelectric conversion units 34L, 34R similar to the imaging / 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) When a light shielding 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 shielding 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 shielding 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 shielding member 35.

[0141] (Variation 4) The number of types, number of arrangements, and arrangement of the focus detection pixels 302 may be different from those in the above-described embodiment. Similarly, the number of types, number of arrangements, 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 be different from those in the above-described embodiment.

[0142] Fig. 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. 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 region 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 of 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, and may be, for example, the Y-axis direction. In this case, a pair of photoelectric conversion units 34T, 34B divided in the Y-axis direction may be provided, as shown in FIG. 22(b), for example.

[0144] Furthermore, both the X-axis direction and the Y-axis direction can be set as the focus detection direction. For example, as shown in FIG. 22(c), four photoelectric conversion units 34a, 34b, 34c, and 34d are provided. In this case, if the light reception signals of the two photoelectric conversion units 34a and 34c arranged on the left side of the paper are added, a signal equivalent to the light reception signal of the photoelectric conversion unit 34L shown in FIG. 22(a) is obtained. Also, if the light reception signals of the two photoelectric conversion units 34a and 34b arranged on the upper side of the paper are added, a signal equivalent to the light reception signal of the photoelectric conversion unit 34T shown in FIG. 22(b) is obtained. Therefore, if the imaging and focus detection pixel 301 is configured as shown in FIG. 22(c) and a focus detection pixel 302 having a photoelectric conversion unit with a smaller width in the X-axis direction and the Y-axis direction of the four photoelectric conversion units 34a, 34b, 34c, and 34d is provided, both the X-axis direction and the Y-axis direction become the focus detection direction.

[0145] As long as the characteristics of the present invention are not impaired, 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. [Explanation of symbols]

[0146] Reference Signs List 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 section, 222... second focus detection section, 230... focus adjustment section, 240... ROM, 250... display device, 301, 301a, 301b... imaging and focus detection pixels, 302... focus detection pixel

Claims

1. a plurality of first pixel columns each having a plurality of first pixels that receive light transmitted through the imaging optical system and output a signal used for focus detection; a plurality of second pixel rows each including a plurality of second pixels that receive light transmitted through the imaging optical system and output a signal used for focus detection; a circuit for selecting one of the first pixel row and the second pixel row based on information regarding an exit pupil position of the imaging optical system; Equipped with the first pixel receives light through an opening provided at a first position of a light-shielding portion; the second pixel receives light through an opening provided at a second position of the light blocking portion that is different from the first position; a first region in which only one of the plurality of first pixel rows and the plurality of second pixel rows is arranged, and a second region having an image height higher than that of the first region and in which both the plurality of first pixel rows and the plurality of second pixel rows are arranged, Image sensor.

2. the circuit 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 1 .

3. the first pixel includes a pair of pixels that 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. 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 a center of an imaging surface. The imaging device according to claim 1 .

6. The first region and the second region have the same area. The imaging device according to claim 1 .

7. an image sensor including: a plurality of first pixel rows having a plurality of first pixels that receive light transmitted through an imaging optical system and output a signal used for focus detection; and a plurality of second pixel rows having a plurality of second pixels that receive light transmitted through the imaging optical system and output a signal used for focus detection; 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; Equipped with the first pixel receives light through an opening provided at a first position of a light-shielding portion; the second pixel receives light through an opening provided at a second position of the light blocking portion that is different from the first position; a first region in which only one of the plurality of first pixel rows and the plurality of second pixel rows is arranged, and a second region having an image height higher than that of the first region and in which both the plurality of first pixel rows and the plurality of second pixel rows are arranged, Imaging device.

8. 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 7.

9. the first pixel includes a pair of pixels that 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.

9. The imaging device according to claim 7 or 8.

10. 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 claim 7 .

11. The first region is a region including a center of an imaging surface. The imaging device according to claim 7 .

12. The first region and the second region have the same area. The imaging device according to claim 7 .

Images