JP2009244429A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of performing an AF anywhere in an imaging area in a live view mode, and which is excellent in focusing accuracy and focusing speed. <P>SOLUTION: The digital camera is configured to perform a phase difference AF with reference to the imaging area of an imaging device 6 in the live view mode, and perform a contrast AF with reference to an AF frame set in the imaging area by using a result obtained by the phase difference AF and information on the position of a photographic lens 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus.

  As a focus for live view of a digital camera, autofocus using a contrast detection method (hereinafter, abbreviated as “contrast AF” or “TV-AF”) is the mainstream. On the other hand, since digital single-lens reflex cameras require continuous shooting performance and moving object tracking performance, AF using a phase difference detection method with a fast focusing speed (hereinafter referred to as “phase difference AF”) is suitable. When TV-AF is used for focusing at the time of view, the focusing speed becomes slow.

  Therefore, Patent Document 1 proposes a hybrid AF that can use two AF methods of phase difference AF and TV-AF during live view. Patent Document 1 divides a photographing optical path into a plurality of optical paths, a main mirror constituted by a half mirror, and one of the divided optical paths into an in-focus position determination element and an optical path for guiding the other into an imaging element. And a sub mirror composed of a half mirror. The main mirror and the sub-mirror move in the photographing optical path when waiting for photographing and detect the in-focus position by the focus detection element and the image sensor, and move out of the photographing optical path during photographing and detect the in-focus position by the image sensor.

There exists patent document 2 as another patent document.
JP 2006-251065 A JP 2005-283750 A

  However, in Patent Document 1, the place where the phase difference AF can be performed within the imaging region is limited to the place where the image detection sensor is arranged, and there is a possibility that a release time lag may occur due to the movement of the main mirror and the sub mirror when shooting. is there.

  An object of the present invention is to provide an imaging apparatus that can perform AF anywhere in an imaging region during live view and has excellent focusing accuracy and focusing speed.

An imaging apparatus as one aspect of the present invention includes a mode setting unit that sets a live view mode;
A plurality of shooting pixels each including light that passes through the entire exit pupil of an imaging lens that includes a focus lens and forms an image of the subject, and generates the image of the subject; and each of the exit pupils of the imaging lens A plurality of focus detection pixels that receive light passing through a partial area of the imaging lens, and the plurality of focus detection pixels as a whole receive light passing through the entire exit pupil of the photographing lens; A position detection unit that detects a current position of the focus lens of the photographing lens, a frame setting unit that sets a focus detection frame that is a target of focus detection to an arbitrary position in the imaging region of the imaging element, and the frame setting The focus detection by the phase difference detection method is performed on the focus detection frame by calculating the output signal of the focus detection pixel of the focus detection frame set by the unit to calculate the defocus amount of the focus detection frame. ,in front The frame setting unit sets the focus detection of the contrast detection method based on the defocus amount and the in-focus position of the focus lens of the photographing lens obtained from the current position of the focus lens of the photographing lens detected by the position detection unit. And a control unit that performs the focus detection frame.

  According to the present invention, it is possible to provide an imaging apparatus that can perform AF anywhere in the imaging area during live view and has excellent focusing accuracy and focusing speed.

  1 and 2 are sectional views of the digital single-lens reflex camera of this embodiment.

  Reference numeral 1 denotes a camera body. Reference numeral 2 denotes a mount for making a photographic lens 3 to be described later attachable to and detachable from the camera body 1, and has an interface unit for communicating various signals and supplying drive power. Reference numeral 3 denotes an interchangeable photographic lens, which has a focus lens group, a zoom lens group, and a diaphragm device (not shown) inside. 1 and 2 show each lens group as a single lens for convenience. For example, the focus lens group is shown as a focus lens 3a. However, in actuality, it is composed of a complex combination of lens groups with a large number of lenses. 1 and 2 are not intended to limit the focus lens 3a to the front lens of the photographing lens 3. FIG.

  Reference numeral 4 denotes a main mirror composed of a half mirror, which can be rotated according to the operating state of the camera. The main mirror 4 is obliquely arranged in the photographing optical path when observing the subject with the finder, and bends the light beam from the photographing lens 3 and guides it to a finder optical system described later (FIG. 1). The main mirror 4 is retracted from the photographing optical path during photographing or live view, and guides the light flux from the photographing lens 3 to the image sensor 6 described later (FIG. 2). Reference numeral 5 denotes a shutter for controlling incidence of a light beam from the photographing lens 3 to an image sensor 6 to be described later. The shutter 5 is normally closed (FIG. 1) and opened during photographing or live view (FIG. 2).

Reference numeral 6 denotes an image sensor composed of a CMOS image sensor and its peripheral circuits. The image sensor 6 is configured so that all pixels can be independently output. Some pixels are focus detection pixels, and phase difference detection type focus detection (phase difference AF) is possible on the imaging surface. More specifically, the image sensor 6 receives a plurality of shooting pixels each of which receives light passing through the entire exit pupil (EP to be described later) of the shooting lens 3 that forms a subject image and generates a subject image. Have The imaging device 6 further includes a plurality of focus detection pixels that each receive light passing through a partial region (EP _HA and EP _HB described later) of the exit pupil EP of the photographing lens 3. The plurality of focus detection pixels as a whole can receive light passing through the entire exit pupil of the photographing lens 3.

  Reference numeral 7 denotes a sub-mirror that rotates together with the main mirror 4. When the main mirror 4 is obliquely arranged on the photographing optical path, a light beam transmitted through the main mirror 4 is bent toward the AF sensor 8 and guided to the AF sensor 8 (described later). FIG. 1). The sub-mirror 7 rotates together with the main mirror 4 at the time of shooting or live view and retracts from the shooting optical path (FIG. 2). The sub mirror 7 is not a half mirror but shields the image sensor 6. Reference numeral 8 denotes an AF sensor, which includes a secondary imaging lens, an area sensor composed of a plurality of CCDs or CMOSs, and the like, and can perform phase difference AF.

  Reference numeral 9 denotes a focusing plate disposed on the primary image forming surface of the photographing lens 3, a Fresnel lens (condenser lens) is provided on the incident surface, and a subject image (finder image) is formed on the exit surface. . Reference numeral 10 denotes a finder optical path changing pentaprism that corrects a subject image formed on the exit surface of the focusing plate 9 into an erect image. Reference numerals 11 and 12 are eyepiece lenses. Here, an optical system including the focus plate 9, the pentaprism 10, and the eyepieces 11 and 12 is referred to as a finder optical system.

  Reference numeral 13 denotes an automatic exposure (AE) sensor, which is composed of photodiodes corresponding to respective areas in the multi-divided imaging area, and measures the luminance of the subject image formed on the exit surface of the focusing screen 9. A liquid crystal monitor (display unit) 14 displays captured images and various types of shooting information. The liquid crystal monitor 14 displays an object image (subject image) captured by the image sensor 6 in the live view mode, and is set by the AF controller and the AF controller 33 that can be set by the AF controller setting unit described later. The AF frame is displayed.

  FIG. 3 is a block diagram of a control system of the digital single-lens reflex camera.

  Reference numeral 20 denotes a microcomputer (central processing unit; hereinafter referred to as “MPU”) that controls the camera unit and the entire camera. The MPU (control unit) 20 performs phase difference AF on the AF frame by calculating an output signal of the focus detection pixel of the AF frame set by the multi-controller 33 which is a frame setting unit to be described later, thereby performing the focus detection frame. The amount of defocus is calculated. Further, the MPU 20 performs contrast detection focus detection (contrast AF or TV-AF) with the multi-controller 33 on the basis of the focal position of the photographing lens 3 (Ps to be described later) obtained from the defocus amount and the current position of the focus lens 3a. Is performed on the set AF frame. The current position of the focus lens 3a is detected by a position detector 35 described later.

  Reference numeral 21 denotes a memory controller that performs various controls of image data. Reference numeral 22 denotes an EEPROM that stores settings and adjustment data for performing various controls. A lens control circuit 23 in the photographing lens 3 is connected to the MPU 20 via the mount 2 and performs focus adjustment (focus drive) and aperture drive of the focus lens 3a based on each information described later.

  Reference numeral 24 denotes a focus detection circuit that performs accumulation control and readout control of the area sensor of the AF sensor 8 and outputs pixel information of each focus detection point to the MPU 20. The MPU 20 performs known phase difference AF on the pixel information of each focus detection point, and sends the detected focus detection information to the lens control circuit 23 to adjust the focus of the focus lens 3a. A series of operations from focus detection to focus adjustment is referred to as AF operation.

  A photometric circuit 25 outputs a luminance signal from each area of the AE sensor 13 to the MPU 20. The MPU 20 performs A / D conversion of the luminance signal to obtain photometric information of the subject, and uses this photometric information to calculate and set the photographic exposure. A series of operations from obtaining this photometric information to setting the photographic exposure is called an AE operation. A motor driving circuit 26 controls a motor (not shown) that drives the main mirror 4 and a motor (not shown) that charges the shutter 5. Reference numeral 27 denotes a shutter drive circuit that controls power supply to a coil (not shown) for opening and closing the shutter 5. A DC / DC converter 28 converts the voltage of the power source 29 into a voltage necessary for each circuit.

  A release button 30 outputs SW1 and SW2 signals to the MPU 20. SW1 is a switch that is turned on by a first stroke (half-press) operation to start photometry (AE) and AF operations. SW2 is a switch for turning on by a second stroke (full press) operation of the release button to start an exposure operation. Reference numeral 31 denotes a mode button. When an electronic dial 32 described later is operated while being operated, the shooting mode is changed according to the count, and it is determined that the operation is stopped. Reference numeral 32 denotes an electronic dial. An ON signal corresponding to a dial rotation click is output to an up / down counter (not shown) in the MPU 20 and the number thereof is counted. Various numerical values and data are selected according to this count.

  Reference numeral 33 denotes a multi-controller, which is an input device used to select and determine an AF frame (focus detection frame) displayed on the liquid crystal monitor 14 and various modes during a live view described later. The multi-controller 33 can perform input in eight directions of up / down / left / right, diagonal upper right, diagonal lower right, diagonal upper left, diagonal lower left, and input by a push operation. The multi-controller 33 functions as a mode setting unit that sets a live view mode. The multi-controller 33 also functions as a frame setting unit that sets an AF frame that is a focus detection target at an arbitrary position in the imaging region of the imaging device 6. A power button 34 turns on / off the camera when operated.

  A position detector 35 detects the current position of the focus lens 3a. A lens driver 36 drives the focus lens 3a in the optical axis direction. The driving of the focus lens 3 a by the lens dry 36 is controlled by the lens control circuit 23.

  Reference numeral 40 denotes a CDS (correlated double sampling) / AGC (automatic gain adjustment) circuit that samples and holds an image signal output from the image sensor 6 and performs automatic gain adjustment. Reference numeral 41 denotes an A / D converter that converts the analog output of the CDS / AGC circuit 40 into a digital signal. Reference numeral 42 denotes a TG (timing generation) circuit, which supplies a drive signal to the image sensor 6, a sample hold signal to the CDS / AGC circuit 40, and a sample clock signal to the A / D converter 41. Here, the memory controller 21 can receive the image signal output from the image sensor 6 through the CDS / AGC circuit 40 and the A / D converter 41 and detect the focus of the subject image by the TV-AF. .

  Reference numeral 43 denotes an SDRAM (memory) for temporarily recording an image or the like digitally converted by the A / D converter 41. The SDRAM 43 can record the output signal of the focus detection pixels in the entire imaging area of the imaging device 6. Alternatively, the SDRAM 43 performs phase difference AF on the entire imaging region of the imaging device 6 to calculate and record the defocus amount.

  An image processing circuit 44 performs Y / C (luminance signal / color difference signal) separation, white balance correction, γ correction, and the like on the image. An image compression / decompression circuit 45 compresses an image according to a format such as JPEG or decompresses the compressed image. Here, the memory controller 21 can obtain photometric information of the subject by performing image processing on the image signal output from the image sensor 6 by the image processing circuit 44. A D / A converter 46 converts an image into an analog signal in order to display an image recorded on the SDRAM 43 or a medium 48 described later on the liquid crystal monitor 14. Reference numeral 47 denotes an I / F (interface) with the medium 48 for recording and storing images.

  Next, imaging surface phase difference AF by the imaging element 6 will be described. In the present embodiment, an image sensor having a pixel pitch of 8 μm, an effective pixel number of 3000 rows × 4500 columns = 13.5 million pixels, and an image pickup screen size of 36 mm × 24 mm is described as an example. The image sensor 6 is a two-dimensional single-plate color sensor in which a Bayer array primary color mosaic filter is formed on-chip on a light receiving pixel.

  4 to 6 are diagrams illustrating the structures of the imaging pixels and the focus detection pixels. In the present embodiment, among 4 pixels of 2 rows × 2 columns, pixels having G (green) spectral sensitivity are arranged in 2 diagonal pixels, and R (red) and B (blue) are arranged in the other 2 pixels. A Bayer arrangement in which one pixel having spectral sensitivity is arranged is employed. In addition, focus detection pixels having a structure described later are distributed and arranged in a predetermined rule between the Bayer arrays.

FIG. 4 shows the arrangement and structure of the imaging pixels. FIG. 4A is a plan view of 2 × 2 imaging pixels. As is well known, in the Bayer array, G pixels are arranged diagonally, and R and B pixels are arranged in the other two pixels. A structure of 2 rows × 2 columns is repeatedly arranged. FIG. 4B is a cross-sectional view taken along the line AA in FIG. ML denotes an on-chip microlens arranged in front of each pixel, CF _R is a color filter, CF _G of R (red), a G (green) color filter. PD (Photo Diode) schematically shows a photoelectric conversion element of a CMOS image sensor. CL (Contact Layer) is a wiring layer for forming signal lines for transmitting various signals in the CMOS image sensor. TL (Taking Lens) schematically shows a photographing optical system of the photographing lens 3.

  Here, the on-chip microlens ML and the photoelectric conversion element PD of the imaging pixel are configured to capture the light beam that has passed through the photographing optical system TL as effectively as possible. In other words, the exit pupil EP (Exit Pupil) of the photographing optical system TL and the photoelectric conversion element PD are in a conjugate relationship by the microlens ML, and the effective area of the photoelectric conversion element is designed to be large. In FIG. 4B, the incident light beam of the R pixel has been described, but the G pixel and the B (blue) pixel have the same structure. Therefore, the exit pupil EP corresponding to each RGB pixel for imaging has a large diameter, and the S / N of the image signal is improved by efficiently taking in the light flux (photon) from the subject.

FIG. 5 shows the arrangement and structure of focus detection pixels for performing pupil division in the horizontal direction (left-right direction or horizontal direction) of the photographing optical system. Here, the horizontal direction is along a straight line that is orthogonal to the optical axis and extends in the horizontal direction when the imaging apparatus is held so that the optical axis of the imaging optical system and the long side of the imaging region are parallel to the ground. Refers to the direction. FIG. 5A is a plan view of pixels of 2 rows × 2 columns including focus detection pixels. When obtaining an image signal for recording or viewing, the main component of luminance information is acquired by G pixels. Since human image recognition characteristics are sensitive to luminance information, image quality degradation is easily recognized when G pixels are lost. On the other hand, the R pixel or the B pixel is a pixel that acquires color information (color difference information). However, since human visual characteristics are insensitive to color information, the pixel that acquires color information has some defects. However, image quality degradation is difficult to recognize. Therefore, in the present embodiment, among the pixels of 2 rows × 2 columns, the G pixel is left as an imaging pixel, and the R pixel and the B pixel are replaced with focus detection pixels. The focus detection pixels are denoted as S _HA and S _HB in FIG.

FIG. 5B is a cross-sectional view taken along the line AA in FIG. The microlens ML and the photoelectric conversion element PD have the same structure as the imaging pixel shown in FIG. In this embodiment, since the signal of the focus detection pixel is not used for image generation, a transparent film CF _W (white) is disposed instead of the color separation color filter. Further, since pupil division is performed by the image sensor 6, the opening of the wiring layer CL is deviated in one direction with respect to the center line of the microlens ML. Specifically, the pixel S _HA and the opening OP _HA are biased to the right and receive the light flux that has passed through the left exit pupil EP _HA of the imaging optical system TL. Opening _{OP HB} of the pixel _{S HB,} and receives the light beam that has passed through the right exit pupil _{EP HB} of the photographing optical system TL deviate to the left. Pixels _SHA are regularly arranged in the horizontal direction, and a subject image acquired by these pixel groups is defined as an A image. The pixels _SHB are also regularly arranged in the horizontal direction, and the subject image acquired by these pixel groups is defined as a B image. Then, by detecting the relative position between the A image and the B image, the amount of defocus (defocus amount) of the subject image can be detected. In the pixels S _HA and S _HB , focus detection is possible for an object having a luminance distribution in the horizontal direction of the imaging region, for example, a vertical line, but focus detection is not possible for a horizontal line having a luminance distribution in the vertical direction. Therefore, in this embodiment, the latter is also provided with pixels that perform pupil division in the vertical direction (longitudinal direction) of the photographing optical system so that the focus state can be detected.

FIG. 6 shows the arrangement and structure of focus detection pixels for performing pupil division in the vertical direction (vertical direction or vertical direction) of the photographing optical system. Here, the vertical direction is along a straight line that is perpendicular to the optical axis and extends in the vertical direction when the imaging device is set so that the optical axis of the imaging optical system and the long side of the imaging region are parallel to the ground. The direction. FIG. 6A is a plan view of pixels of 2 rows × 2 columns including focus detection pixels. As in FIG. 5A, G pixels are left as imaging pixels, and R pixels and B pixels are used. Focus detection pixels are used. The focus detection pixels are denoted as S _VC and S _VD in FIG.

FIG. 6B is a sectional view taken along the line AA in FIG. While the pixel in FIG. 5B has a structure in which the pupil is separated in the horizontal direction, the pixel in FIG. 6B has a vertical pupil separation direction, but the other pixels have the same structure. is there. Pixel openings OP _VC of S _VC and receives the light beam that has passed through the upper exit pupil EP _VC of the photographing optical system TL deviate downward. Similarly, the opening OP _VD of the pixel S _VD is biased upward and receives the light beam that has passed through the lower exit pupil EP _VD of the imaging optical system TL. The pixels _SVC are regularly arranged in the vertical direction, and a subject image acquired by these pixel groups is defined as a C image. The pixels _SVD are also regularly arranged in the vertical direction, and the subject image acquired by these pixel groups is taken as a D image. Then, by detecting the relative positions of the C image and the D image, it is possible to detect the focus shift amount (defocus amount) of the subject image having the luminance distribution in the vertical direction.

  7 to 9 are diagrams for explaining the arrangement rules of the imaging pixels and the focus detection pixels shown in FIGS. 4 to 6. FIG. 7 is a diagram for explaining a minimum unit arrangement rule in a case where focus detection pixels are discretely arranged between imaging pixels.

In FIG. 7, a square region of 10 rows × 10 columns = 100 pixels is defined as one block. In the upper left block BLK _H (1, 1), the lower left R pixel and B pixel are replaced with a set of focus detection pixels S _HA and S _HB that perform pupil division in the horizontal direction. In the block BLK _V (1,2) on the right side, the lower left R pixel and B pixel are similarly replaced with a set of focus detection pixels S _VC and S _VD that perform pupil division in the vertical direction. The pixel arrangement of the block BLK _V (2,1) adjacent below the first block BLK _H (1,1) is the same as that of the block BLK _V (1,2). The pixel arrangement of the block BLK _H (2, 2) on the right side is the same as that of the leading block BLK _H (1, 1). When this arrangement rule is generalized, in block BLK (i, j), if i + j is an even number, a focus detection pixel for horizontal pupil division is arranged, and if i + j is an odd number, focus detection pixels for vertical pupil division are used. Pixels are arranged. Then, a 2 × 2 = 4 block in FIG. 7, that is, an area of 20 rows × 20 columns = 400 pixels is defined as a cluster as an upper array unit of the block.

FIG. 8 is a diagram for explaining an arrangement rule in units of clusters. In FIG. 8, the upper left cluster composed of 20 rows × 20 columns = 400 pixels is assumed to be CST (u, w) = CST (1,1). In the cluster CST (1, 1), the lower left R pixel and B pixel of each block are replaced with focus detection pixels S _HA and S _HB or S _VC and S _VD . In the cluster CST (1, 2) on the right side, the focus detection pixels in the block are arranged at positions shifted upward by two pixels with respect to the cluster CST (1, 1). Further, in the cluster CST (2, 1) adjacent below the first cluster CST (1, 1), the arrangement of the focus detection pixels in the block is 2 in the right direction with respect to the cluster CST (1, 1). It is arranged at a position shifted by pixels. When the above rules are applied, the arrangement shown in FIG. 8 is obtained.

  This arrangement rule is generalized as follows. The coordinates of the focus detection pixels are defined by the coordinates of the upper left pixel of the four pixels including the G pixel shown in FIG. 5 or 6 as one unit (pair). In the coordinates in each block, the upper left is (1, 1), and the lower direction and the right direction are positive. In the cluster CST (u, w), the horizontal coordinate of the focus detection pixel pair in each block is 2 × u−1, and the vertical coordinate is 11-2 × w. Then, 5 × 5 = 25 clusters in FIG. 8, that is, an area of 100 rows × 100 columns = 10,000 pixels is defined as a field as an upper array unit of the clusters.

  FIG. 9 is a diagram for explaining an arrangement rule in units of fields. In FIG. 9, the upper left field composed of 100 rows × 100 columns = 10,000 pixels is assumed to be FLD (q, r) = FLD (1,1). In this embodiment, all the fields FLD (q, r) have the same arrangement as that of the first field FLD (1,1). Therefore, when 45 fields FLD (q, r) are arranged in the horizontal direction and 30 fields are arranged in the vertical direction, the imaging area of 3000 rows × 4500 columns = 13.5 million pixels is composed of 1350 fields FLD (q, r). . The focus detection pixels can be uniformly distributed over the entire imaging region.

  Next, a group of pixels and a signal addition method at the time of focus detection will be described with reference to FIGS.

  FIG. 10 is a diagram for explaining a pixel grouping method in the case of performing focus detection in the lateral shift direction of the subject image formed by the photographing optical system. The focus detection in the lateral shift direction performs phase difference focus detection using the focus detection pixels for dividing the exit pupil of the photographing optical system in the horizontal direction (horizontal direction or left-right direction) described in FIG. Refers to that.

The pixel arrangement shown in FIG. 10 is the same as that described with reference to FIG. 8, but when focus detection is performed, a total of 10 blocks of 1 block in the horizontal direction and 10 blocks in the vertical direction are grouped and defined as a section. To do. A plurality of sections SCT _H (k) arranged in the horizontal direction are connected to form one focus detection region. One focus detection area as an example in the present embodiment is configured by connecting ten sections from section _SCT H (1) to the section _SCT H (10). That is, an area of 100 rows × 100 columns = 10,000 pixels is one focus detection area. This is the same area as one field, and is set so that there are 1350 fixed focus detection areas in the imaging area as described in FIG. Of course, there are various setting methods, and it is possible to set the variable focus detection region at an arbitrary position in the imaging region by connecting a plurality of sections SCT _H (k) at an arbitrary position in the imaging region according to the subject.

Here, one section includes five pixels S _HA that performs one pupil division in the horizontal direction and five pixels S _HB that perform the other pupil division. Therefore, in the present embodiment, the outputs of the five _SHAs are added to form a signal of one pixel, and one AF signal of one image signal (referred to as A image) for phase difference calculation is obtained. Similarly, the outputs of the five _SHBs are added to form a signal of one pixel, and 1AF pixel of the other image signal (referred to as B image) for phase difference calculation is obtained.

FIG. 11 is a diagram for explaining the subject image capturing capability in one section. FIG. 11 is a cut-out section SCT _H (1) at the left end of FIG. The horizontal line PRJ _H shown at the lower end is a first projection line extending in the pupil division direction of the focus detection pixels S _HA and S _HB , and the vertical line PRJ _V shown at the right end is a pupil division. It is the 2nd projection axis | shaft extended | stretched in the direction orthogonal to a direction. Here, all the pixels S _HA in one section are added, and S _HB is also added. Therefore, when one section is regarded as one AF pixel, pixels S _HA and S _HB are alternately arranged densely when the light receiving portion included in one AF pixel is projected onto the projection axis PRJ _H in the pupil division direction. I understand. If the arrangement pitch of the pixels S _{HA on} the projection axis PRJ _H in the pupil division direction at this time is P1, P1 = PH _H = 2 (unit is pixel). When expressed by the spatial frequency F1 instead of the pitch, F1 = 0.5 (unit is pixel / pixel). Similarly, the arrangement pitch of the pixels S _HB on the projection axis PRJ _H is P1 = 2 (unit is pixel), and F1 = 0.5 (unit is pixel / pixel) in the spatial frequency notation.

On the other hand, when projecting the light receiving portions included in one AF pixel projection axis PRJ _V in the pupil division direction and the perpendicular direction, the pixel S _HA and S _HB is seen that aligned sparsely. When the arrangement pitch of the pixels S _{HA on} the projection axis PRJ _{V at} this time is P2, P2 = PH _V = 20 (unit is pixel). When expressed by the spatial frequency F2 instead of the pitch, F2 = 0.05 (unit: pixel / pixel). Similarly, the arrangement pitch of the pixels S _HB on the projection axis PRJ _V is also P2 = 20 (unit is pixel), and F2 = 0.05 (unit is pixel / pixel) in the spatial frequency notation.

  In other words, the AF pixels in the present embodiment have the same pitch in arrangement in the pupil division direction and the direction orthogonal thereto with respect to the dispersion characteristics before grouping. However, the sampling error in the pupil division direction is reduced by making the group shape at the time of grouping rectangular. Specifically, the maximum dimension L1 in the pupil division direction of one section is 10 pixels, and the maximum dimension L2 in the direction orthogonal to the pupil division is 100 pixels. That is, by setting the section size to L1 <L2, the sampling frequency F1 in the pupil division direction is set to a high frequency (dense), and the sampling frequency F2 in a direction orthogonal to the sampling frequency F1 is set to a low frequency (sparse).

  FIG. 12 is a diagram for explaining a pixel grouping method in the case where focus detection in the direction of vertical shift of a subject image formed by a photographing optical system is performed. The focus detection in the longitudinal shift direction is the phase difference focus detection using the focus detection pixels for dividing the exit pupil of the photographing optical system in the vertical direction (vertical direction or vertical direction) described in FIG. To do. That is, it corresponds to the one obtained by rotating FIG. 10 by 90 degrees.

The pixel arrangement shown in FIG. 12 is the same as that described with reference to FIG. 8, but for focus detection, a total of 10 blocks, 10 blocks in the horizontal direction and 1 block in the vertical direction, are defined as a group. To do. A plurality of sections SCT _V (k) arranged in the vertical direction are connected to form one focus detection region. One focus detection area as an example in the present embodiment is configured by connecting ten sections from section _SCT V (1) to the section _SCT V (10). That is, an area of 100 rows × 100 columns = 10,000 pixels is one focus detection area. This is the same area as one field, and is set so that there are 1350 fixed focus detection areas in the imaging area as described in FIG. Of course, there are various setting methods, and it is possible to set the variable focus detection region at an arbitrary position in the imaging region by connecting a plurality of sections SCT _V (k) at an arbitrary position in the imaging region according to the subject.

Here, one section includes five pixels _SVC that perform one pupil division in the vertical direction and five pixels _SVD that perform the other pupil division. Therefore, in the present embodiment, the outputs of the five _SVCs are added to form a signal of one pixel, and one AF signal of one image signal (referred to as a C image) for phase difference calculation is obtained. Similarly, the outputs of the five _SVDs are added to form a signal of one pixel, and 1AF pixel of the other image signal (referred to as D image) for phase difference calculation is obtained.

FIG. 13 is a diagram for explaining the capturing ability of the subject image in one section, and is equivalent to the one obtained by rotating FIG. 11 by 90 degrees. FIG. 13 is a cut-out section SCT _V (1) at the upper end of FIG. The vertical line PRJ _V shown at the right end is a third projection axis extending in the pupil division direction of the focus detection pixels S _VC and S _VD , and the horizontal line PRJ _H shown at the lower end is orthogonal to the pupil division direction. It is the 4th projection axis extended in the direction. Also in FIG. 12, all the pixels S _VC in one section are added, and S _VD is also added. Therefore, when one section is regarded as one AF pixel, it can be seen that pixels S _VC and S _VD are arranged densely alternately when the light receiving portion included in the one AF pixel is projected onto the projection axis PRJ _V in the pupil division direction. When the arrangement pitch of the pixels S _{VC on} the projection axis PRJ _V in the pupil division direction at this time is P1, P1 = PV _V = 2 (the unit is a pixel). When expressed by the spatial frequency F1 instead of the pitch, F1 = 0.5 (unit is pixel / pixel). Similarly, the arrangement pitch of the pixels S _VD on the projection axis PRJ _V is P1 = 2 (unit is pixel), and F1 = 0.5 (unit is pixel / pixel) in the spatial frequency notation.

On the other hand, when projecting the light receiving portions included in one AF pixel projection axis PRJ _H pupil division direction and the orthogonal direction, the pixels S _VC and S _VD is seen that aligned sparsely. If the arrangement pitch of the pixels S _{VC on} the projection axis PRJ _{H at} this time is P2, then P2 = PV _H = 20 (the unit is a pixel). When expressed by the spatial frequency F2 instead of the pitch, F2 = 0.05 (unit: pixel / pixel). Similarly, the arrangement pitch of the pixels S _VD on the projection axis PRJ _V is also P2 = 20 (unit is pixel), and F2 = 0.05 (unit is pixel / pixel) in the spatial frequency notation.

  As described above, the sampling characteristics of the AF pixels in FIG. 13 are the same as those in FIG. 11, that is, F1> F2 when the pupil division direction is taken as a reference. This is because the section dimension L1 in the pupil division direction and the dimension L2 in the direction perpendicular to this also satisfy L1 <L2 in the section of FIG. Thus, luminance information in the pupil division direction can be accurately detected even for a subject with a high spatial frequency, and the S / N ratio of the focus detection signal is improved by adding a plurality of pixels even when the subject luminance is low. be able to.

FIG. 14 is a diagram conceptually illustrating the pupil division function of the image sensor in the present embodiment. OBJ is a subject, and IMG is a subject image. As described with reference to FIG. 4, the imaging pixel receives the light beam that has passed through the entire exit pupil EP of the imaging optical system TL. On the other hand, the focus detection pixel has a pupil division function as described with reference to FIGS. Specifically, the pixel S _{HA in} FIG. 5 receives the light beam L _HA that has passed through the left pupil when viewed from the imaging surface, that is, the light beam that has passed through the pupil EP _HA in FIG. Similarly, the pixels S _HB , S _VC, and S _VD respectively receive the light beams L _HB , L _HC , and L _HD that have passed through the pupils EP _HB , EP _VC, and EP _VD , respectively. Since the focus detection pixels are distributed over the entire area of the image sensor 6 as described with reference to FIG. 9, the focus detection is also possible over the entire imaging area.

  FIG. 15 is a diagram for explaining an AF operation during live view, and shows a state in which an image is displayed on the liquid crystal monitor 14 during live view. In the subject image formed on the imaging surface, a person is shown in the center, a foreground fence in the lower left, and a distant mountain in the upper right, which are displayed on the screen. An AF frame is displayed at the center of the screen. In this embodiment, as an example, the AF frame is set to have a size of 6 fields in the horizontal direction and 6 fields in the vertical direction. Further, the AF frame can be moved to an arbitrary position in the imaging region in accordance with an input signal of the multi-controller 33. In the present embodiment, as an example, the movement of the AF frame is in units of one field. Of course, the amount of movement varies, and it may be one section unit or one pixel unit.

First, the imaging surface phase difference AF will be described. As shown in FIG. 9, the focus detection pixels are arranged with equal density over the entire imaging region, as shown in FIG. 9, the pixel pairs S _HA and S _HB for detecting lateral deviation and the pixel pairs S _VC and S _VD for detecting vertical deviation. Has been. At the time of lateral shift detection, AF pixel signals for phase difference calculation are grouped as shown in FIGS. In addition, when detecting vertical shift, AF pixel signals for phase difference calculation are grouped as shown in FIGS. Therefore, it is possible to set a focus detection area for detecting lateral deviation and vertical deviation at an arbitrary position in the imaging area. As described above, in the present embodiment, as an example, the focus detection area is set to the same area as the field.

In FIG. 15, a human face exists in the center of the screen. Therefore, when the presence of a face is detected by a known face recognition technique, an AF frame is displayed in a portion detected as a face area, and focus detection in the AF frame is performed. First, AF frame areas AFAR _H (1) to (6) in which a plurality of focus detection areas are connected to detect lateral deviation, and AF frame areas AFAR _V (1) to (6) in which a plurality of focus detection areas are connected to detect vertical deviation. 6) is set.

The AF frame area AFAR _H (1) for lateral shift detection includes six fields from the field FLD (13, 21) to the field FLD (13, 26) in the focus detection area in the first row from the top in the AF frame. It is connected. The AF frame area AFAR _H (2) connects the field FLD (14, 21) to the field FLD (14, 26) in the focus detection area in the second row from the top in the AF frame. The AF frame area AFAR _H (3) connects the field FLD (15, 21) to the field FLD (15, 26) in the focus detection area in the third row from the top in the AF frame. The AF frame area AFAR _H (4) connects the field FLD (16, 21) to the field FLD (16, 26) in the focus detection area in the fourth row from the top in the AF frame. The AF frame area AFAR _H (5) connects the field FLD (17, 21) to the field FLD (17, 26) of the focus detection area in the fifth row from the top in the AF frame. The AF frame area AFAR _H (6) connects the field FLD (18, 21) to the field FLD (18, 26) of the focus detection area in the fifth row from the top in the AF frame.

The AF frame area AFAR _V (1) for detecting vertical deviation is equivalent to six fields from the field FLD (13, 21) to the field FLD (18, 21) in the focus detection area in the first column from the left in the AF frame. Are connected. The AF frame area AFAR _V (2) connects the field FLD (13, 22) to the field FLD (18, 22) in the focus detection area in the second column from the left in the AF frame. The AF frame area AFAR _V (3) connects the field FLD (13, 23) to the field FLD (18, 23) of the focus detection area in the first column from the left in the AF frame. The AF frame area AFAR _V (4) connects the field FLD (13, 24) to the field FLD (18, 24) of the focus detection area in the first column from the left in the AF frame. The AF frame area AFAR _V (5) connects the field FLD (13, 25) to the field FLD (18, 25) of the focus detection area in the fifth column from the left in the AF frame. The AF frame area AFAR _V (6) connects the field FLD (13, 26) to the field FLD (18, 26) of the focus detection area in the sixth column from the left in the AF frame.

FIG. 15 shows AF frame regions for detecting lateral shift and vertical shift as AFAR _H (3) and AFAR _V (5) one by one, and the other five regions are not shown. 5 focus detection pixels S _HA included in each section of the AF frame area AFAR _H (3) are added and connected over 60 sections (= 1 focus detection area 10 sections × AF frame width 6 fields). The detected A image signal for phase difference detection is AFSIG _H (A3). Similarly, adding the five focus detection pixels S _HB of each section, B image signal for phase difference detection which is connected over this 60 section is AFSIGh (B3). By calculating the relative lateral shift amount between the A image signal AFSIG _H (A3) and the B image signal AFSIG _H (B3) by a known correlation calculation, the defocus amount (defocus amount) of the subject is obtained. Similarly, the defocus amount of the subject is obtained in each of the AF frame areas AFAR _H (1) to (6).

The same applies to the AF frame area AFAR _V (5). That is, five focus detection pixels _SHC included in each section are added, and connected for 60 sections (= 1 focus detection region 10 sections × AF frame height 6 fields). The C image signal is AFSIG _V (C5). Further, by adding the five focus detection pixels _{S HD} of each section, D image signal for phase difference detection which is connected over this 60 section is AFSIG _V (D5). Then, by calculating the relative lateral shift amount between the C image signal AFSIG _V (C5) and the D image signal AFSIG _V (D5) by a known correlation calculation, the defocus amount (defocus amount) of the subject is obtained. Similarly, the defocus amount of the subject is obtained in each of the AF frame areas AFAR _V (1) to (6).

  Then, by comparing the defocus amounts of the total 12 detected in the lateral and vertical misalignment AF frame areas and adopting a highly reliable value, the defocus amount in the AF frame can be obtained. Here, the reliability refers to the degree of coincidence between the two images. When the degree of coincidence between the two images is good, the reliability of the focus detection result is generally high. Therefore, when there are focus detection results of a plurality of focus detection areas, highly reliable information is preferentially used. Further, instead of reliability, the defocus amount in the AF frame may be determined by a method such as an average value of a total of 12 defocus amounts or the closest value among them.

  In the above description, the defocus amount of the AF frame region is obtained from the image signal obtained by connecting all sections (60 sections) of the AF frame region. However, the amount of defocus of each of the six focus detection areas constituting the AF frame area is obtained, and the values within the AF frame area are determined by a method such as a highly reliable value, the closest value, or an average value. The amount of defocus can be obtained. Further, a method of obtaining the defocus amount of each of the 36 focus detection areas in the AF frame without setting the AF frame area, and obtaining a highly reliable value, the closest value, or an average value among them. Thus, the defocus amount in the AF frame can be obtained.

On the other hand, when the AF frame is moved to the lower left portion of the screen, similarly, the AF frame area can be reset to detect the lateral shift and the vertical shift, and the defocus amount of the subject can be obtained. However, since the vertical line component is the main component, that is, it has a luminance distribution in the horizontal direction, it can be determined that the subject is suitable for detecting lateral deviation. Therefore, only the AF frame area AFAR _H (n) for lateral shift detection is set, and the lateral shift amount is calculated from the A image signal and the B image signal in the same manner as the AF frame area AFAR _H (3), and the subject. The amount of defocus can be obtained.

  Here, the description has been given of obtaining the defocus amount on the assumption that the AF frame region is set. However, even if the AF frame area is not set, the lateral shift amount is calculated from the A image signal and the B image signal in each focus detection area, and highly reliable information is obtained from the focus detection results of the plurality of focus detection areas. Thus, the defocus amount of the subject can be obtained. That is, the amount of defocus of the face portion of the person at the center of the screen, which is determined as the main subject by face recognition, is calculated at the same time as the amount of defocus of another subject (here, the bottom left fence) in the imaging area. Is possible.

Also, when the AF frame is moved to the top right corner of the screen, the AF defocus amount can be obtained by setting the AF frame region for detecting lateral shift and vertical shift as described above. However, since the horizontal line component is the main component, that is, it has a luminance distribution in the vertical direction, it can be determined that the subject is suitable for detecting vertical shift. For this reason, only the AF frame area AFAR _V (n) for detecting the vertical deviation is set, and the lateral deviation amount is calculated from the C image signal and the D image signal in the same manner as the AF frame area AFAR _V (5). The amount of defocus of the subject can also be obtained.

  Here, the description has been given of obtaining the defocus amount on the assumption that the AF frame region is set. However, even if the AF frame area is not set, the lateral shift amount is calculated from the C image signal and the D image signal in each focus detection area, and highly reliable information is obtained from the focus detection results of the plurality of focus detection areas. Thus, the defocus amount of the subject can be obtained. That is, the amount of defocus of the face portion of the person at the center of the screen, which is determined to be the main subject by face recognition, and the amount of defocus of another subject (here, the mountain at the upper right of the screen) in the imaging area is obtained. Is possible.

  As described above, in the present embodiment, since the focus detection area for detecting the lateral shift and the vertical shift is set in the entire area of the image sensor 6, the projection position of the subject and the directionality of the luminance distribution vary. In addition, focus detection by imaging surface phase difference AF can be performed in the entire imaging region.

  Next, TV-AF will be described. Originally, it is ideal to perform AF only with imaging plane phase difference AF. However, in reality, the focusing accuracy is inferior to that of TV-AF due to problems such as eccentricity of the microlens ML due to manufacturing errors of the image sensor 6 and pupil vignetting due to the F value and image height of the photographing lens 3. There is. Therefore, in this embodiment, in order to keep the focusing accuracy high in any case, TV-AF based on the amount of defocus obtained by the imaging plane phase difference AF is performed on the image in the AF frame.

FIG. 16 is a diagram showing the relationship between the position of the focus lens 3a in the photographing lens 3 and the contrast value with respect to the image in the AF frame. From the current position of the defocus amount and the focus lens 3a of the object obtained by the image pickup surface phase difference AF, it obtains the focus position P _S of the focus lens 3a. And as an example in the present embodiment, and the focus position P _S, the front-rear F [delta] position _{(P S -Fδ, P S +} Fδ) to the three drives the focus lens 3a, 3 images obtained from the respective positions allowing for the determination of the position _{P C} focus by TV-AF from. Here, F represents the aperture value of the taking lens 3, and δ represents an allowable circle of confusion.

In TV-AF, since it is not known where the contrast peak is, it is necessary to drive the focus lens 3a from the infinite position to the closest position, acquire a plurality of images during that time, and perform peak detection. The drive amount is large and it takes time to focus. However, in the present embodiment, the focus lens 3a is because it can peak detected driving in the focus position P _S and its front and rear, can be shortened less focus time driving amount.

  As described above, in the present embodiment, since TV-AF based on the imaging surface phase difference AF result is performed on the image in the AF frame, AF can be performed anywhere in the imaging region, and the focusing accuracy is high. AF with high focusing time and short focusing time is possible.

  Next, the operation of the digital single-lens reflex camera of the present embodiment will be described using the control flows of FIGS. FIG. 17 is a main flow showing the basic operation of the digital single-lens reflex camera.

  In S101, the user operates the power button 34 to turn on the camera. When the power is turned on, the MPU 20 checks the operation of each actuator and the image sensor 6 in the camera. Then, the memory contents and the initialization state of the execution program are detected, and the shooting preparation operation is executed. In S102, various buttons are operated to perform various camera settings. For example, the mode button 31 is operated to select a shooting mode, or the electronic dial 32 is operated to set the shutter speed and the aperture.

  In S103, it is determined whether or not the live view mode is set by the multi-controller 33. If the live view mode is set, the process proceeds to S111 of the live view mode routine. If not set, S104 of the normal mode routine is set. Proceed to

  First, an operation routine in a normal mode (a normal use mode of a single-lens reflex camera in which a user takes a picture through a viewfinder) is described. In S104, it is determined whether or not the release button 30 is half-pressed and SW1 is turned on. If it is turned on, the process proceeds to S105, and if it is not turned on, the process waits until it is turned on. In S105, a predetermined AF operation using the AF sensor 8 is performed. In S106, a predetermined AE operation using the AE sensor 13 is performed. In step S107, the focus detection point in the finder is displayed on a display device (not shown). In S108, it is determined whether or not the release button 30 is fully pressed and the SW2 is turned on. If it is turned on, the process proceeds to S109, and if it is not turned on, the process waits until it is turned on. In S109, a normal photographing routine is executed.

  FIG. 18 is a flowchart of a normal photographing routine. In S131, a motor for driving a mirror (not shown) is controlled by the motor drive circuit 26, and the main mirror 4 and the sub mirror 7 are retracted (mirror up) from the imaging optical path (FIG. 2). In S132, the lens control circuit 23 drives a diaphragm (not shown) in the photographic lens 3 according to the photographic exposure calculated from the AE result. In S133, the shutter 5 is opened and closed by the shutter drive circuit 27. In S <b> 134, an image received by the image sensor 6 is read by the memory controller 21 and temporarily recorded in the SDRAM 43. In S135, defective pixel interpolation of the image signal read out by the memory controller 21 is performed. This is because the output of the focus detection pixel does not have RGB color information for imaging and corresponds to a defective pixel in obtaining an image. Therefore, an image signal is interpolated from information on surrounding imaging pixels. Generate. In S136, the image processing circuit 44 performs image processing such as white balance correction, γ correction, and edge enhancement, and the image compression / decompression circuit 45 compresses the image according to a format such as JPEG. In S <b> 137, the photographed image that has undergone image processing is recorded on the medium 48. In S138, a motor for driving a mirror (not shown) is controlled by the motor drive circuit 26, and the main mirror 4 and the sub mirror 7 retracted from the photographing optical path are driven to an observation position that reflects and guides the photographing light flux to the viewfinder (mirror down). (FIG. 1). In S139, the motor drive circuit 26 controls energization of a charging motor (not shown) to charge the shutter 5. Then, the process returns to S110 in the main routine of FIG. In S110, the user operates the power button 34 to determine whether or not the camera is turned off. If not, the process proceeds to S102 to prepare for the next shooting, and if it is turned off, a series of camera operations are performed. finish.

  Next, an operation routine in the live view mode (a mode in which the user takes a picture using the live view) will be described. In S111, a live view display routine is executed.

  FIG. 19 is a flow of a live view display routine. In S141, a motor for driving a mirror (not shown) is controlled by the motor drive circuit 26, and the main mirror 4 and the sub mirror 7 are retracted (mirror up) from the photographing optical path. In S142, the shutter 5 is opened by the shutter drive circuit 27 (the state shown in FIG. 2 is obtained). In S143, reading of the moving image received by the image sensor 6 by the memory controller 21 is started. In S144, the read moving image is displayed on the liquid crystal monitor 14. The user visually determines this live view image and determines the composition at the time of shooting. Then, the process returns to S112 in the main routine of FIG.

In S112 of FIG. 17, a recognition process is performed to determine whether a face exists in the imaging region. In S113, the AF frame is displayed in gray on the live view image. If it is recognized in S112 that a face is present in the imaging area, an AF frame is displayed in the recognized face area. When it is recognized that no face exists in the imaging area, an AF frame is displayed at the center of the screen. In this embodiment, as shown in FIG. 15, the face of the person at the center of the screen is detected by face recognition, and an AF frame is displayed in the face area. In S114, AF frame area setting is performed. As described above, the AF frame area is set to AF frame areas AFAR _H (1) to (6) for detecting lateral shift and AF frame areas AFAR _V (1) to (6) for detecting vertical shift. . In S115, the multi-controller 33 is operated by the user to determine whether or not the AF frame has been moved. If it has been moved, the process proceeds to S114, and if not, the process proceeds to S116. For example, the AF frame is moved when the face is not recognized and the AF frame is displayed at the center of the screen, but the user wants to focus on a subject other than the center of the screen. In S116, it is determined whether or not the release button 30 is half-pressed and SW1 is turned on. If it is turned on, the process proceeds to S117. If not, the process proceeds to S112 in consideration of the possibility that the composition has been changed. move on. In S118, an imaging surface phase difference AF routine is executed.

  FIG. 20 is a flowchart of the imaging surface phase difference AF routine. In S151, each focus detection pixel included in each focus detection area is read from the image sensor 6 by the memory controller 21. In S152, the memory controller 21 adds the focus detection pixels in each section based on the section structure described in FIG. 10 or FIG. 12, and obtains an AF pixel signal of each section based on the addition result. In S153, it is determined whether or not the AF pixel signal is a signal in the focus detection area in which the AF frame area is set. If the AF frame area is set, the process proceeds to S155, and if not, the process proceeds to S154. In S154, the AF pixel signal in each focus detection area where the AF frame area is not set is temporarily recorded in the SDRAM 43. Then, the process returns to S118 in the main routine of FIG. In S155, the MPU 20 generates two image signals for correlation calculation from the AF pixel signal. In the present embodiment, a pair of signals in which 60 sections such as AFSIGh (A3) and AFSIGh (B3) or AFSIGv (C5) and AFSIGv (D5) shown in FIG. 15 are connected is generated. In S156, the correlation calculation of the two images obtained by the MPU 20 is performed, and the relative displacement amount between the two images is calculated. In S157, the MPU 20 determines the reliability of the correlation calculation result. In S158, the MPU 20 calculates a defocus amount from a highly reliable detection result. Here, one defocus amount is determined and stored in the AF frame. Then, the process returns to S118 in the main routine of FIG.

  In the imaging surface phase difference AF routine, the defocus amount in the focus detection areas is not calculated for the focus detection areas where the AF frame area is not set. This is because it takes a relatively long time for the correlation calculation to be performed by the MPU 20, and at this point, the MPU 20 does not perform correlation calculation for the focus detection area outside the AF frame where the defocus amount itself is unnecessary. This is to shorten the processing time. However, it is temporarily recorded in the state of the AF pixel signal so that it can be calculated immediately when the amount of defocus in those focus detection areas becomes necessary. Of course, the MPU 20 may have a sufficient processing capacity, or may be temporarily recorded by calculating each defocus amount in each focus detection region by performing simultaneous processing in the contrast AF routine described later.

In S118 of FIG. 17, a contrast AF routine is executed. FIG. 21 is a flowchart of the contrast AF routine. In S161, the focus lens focus position is calculated from the defocus amount in the AF frame obtained by the imaging plane phase difference AF routine by the MPU 20 and the current position of the focus lens 3a in the photographing lens 3 detected by the position detector 35. determine the P _S. In S162, the lens control circuit 23 and the lens driver 36 drive the focus lens to the position P _S -Fδ. In S 163, the image received by the image sensor 6 is read by the memory controller 21 and temporarily recorded in the SDRAM 43. In S164, the lens control circuit 23 and the lens driver 36 to drive the focus lens to the position of _{P S.} In S 165, the image received by the image sensor 6 is read by the memory controller 21 and temporarily recorded in the SDRAM 43. In S166, the focus lens is driven to the position of P _S + Fδ by the lens control circuit 23 and the lens driver 36. In S 167, the image received by the image sensor 6 is read by the memory controller 21 and temporarily recorded in the SDRAM 43. In S168, it obtains the position _{P C-focus} from three images recorded temporarily in SDRAM43 by the memory controller 21 by peak detection of the contrast. In S169, the lens control circuit 23 and the lens driver 36 to drive the focus lens to the position of the _{P C.} Then, the process returns to S119 in the main routine of FIG.

  In S119 of FIG. 17, the color of the AF frame is changed from gray to green to notify the user that the AF frame is in focus.

  In S120, an AF frame movement process routine that is a process when the AF frame moves after the photographing lens 3 is focused is executed. FIG. 22 is a flowchart of an AF frame movement processing routine. In S171, it is determined whether or not the multi-controller 33 has been operated by the user. If it has been operated, the process proceeds to S172, and if it has not been operated, the process returns to S121 in the main routine of FIG. In S172, the color of the AF frame is changed from green to gray, and the in-focus display is erased. In S173, the AF frame is moved according to the operation direction and operation time of the multi-controller 33. In S174, the AF frame area is reset at the location where the AF frame has moved. In S175, an imaging plane phase difference AF routine for the reset AF frame area is performed.

  FIG. 23 is a flowchart of the imaging surface phase difference AF routine for the AF frame region. In S181, the AF pixel signal in each focus detection area constituting the reset AF frame area is read from the SDRAM 43. This data is an AF pixel signal in each focus detection area temporarily recorded in the SDRAM 43 in S154 of the imaging surface phase difference AF routine of FIG. In S182, the MPU 20 generates two image signals for correlation calculation. A pair of signals obtained by connecting 60 sections such as AFSIGh (A3) and AFSIGh (B3) or AFSIGv (C5) and AFSIGv (D5) shown in FIG. 15 is generated. In S183, the correlation calculation of the two images obtained by the MPU 20 is performed, and the relative displacement amount between the two images is calculated. In S184, the MPU 20 determines the reliability of the correlation calculation result. In S185, the MPU 20 calculates a defocus amount from a highly reliable detection result. One defocus amount within the AF frame reset here is determined and stored. Then, the process returns to S176 in the AF frame movement processing routine of FIG.

  In the AF frame area imaging plane phase difference AF routine, the AF pixel signal in the focus detection area constituting the reset AF frame area is read and the defocus amount is calculated. However, for example, the defocus amount of each focus detection area may be calculated and recorded by the imaging surface phase difference AF routine. As a result, when the AF frame is moved, the defocus amounts of the six focus detection areas constituting the AF frame area are read out, and the highly reliable value, the closest value, the average value, etc. are obtained. The amount of defocus in the AF frame area can be obtained by this method. Also, without setting the AF frame area, the respective defocus amounts of the 36 focus detection areas in the AF frame are read, and the highly reliable value, the closest value, the average value, etc., among them are set. The amount of defocus in the AF frame moved by this method may be obtained.

  In S176, a contrast AF routine is executed. Since this routine is the same as the contrast AF routine in S118, its description is omitted. In S177, the color of the AF frame is changed from gray to green to notify the user that the AF frame is in focus. Then, the process returns to S121 in the main routine of FIG.

  In the AF frame movement processing routine, AF frame area setting is performed after the user stops moving the AF frame, and the focus lens is focused by the imaging plane phase difference AF and TV-AF. In this case, for example, a subject whose focus position is relatively close to the subject once in-focus operation appears to be almost in focus on the display of the liquid crystal monitor 14, so the AF frame is moved and re-entered. Even if the in-focus operation is performed, the appearance of the live display does not change.

  However, subjects with greatly different in-focus positions appear blurred on the display of the liquid crystal monitor 14. For this reason, if the subject is displayed in a state where the AF frame is aligned in that state and the subject is in focus by the refocusing operation, the position of the AF frame is shifted or the focus position is changed, so that the display on the liquid crystal monitor 14 is changed. The atmosphere may change suddenly. Therefore, following the movement of the AF frame, the lens driver 36 focuses the focus lens 3a, calculates the amount of defocus in the AF frame during movement of the AF frame, and according to the amount of defocus (the amount of defocus is For example, when the focus lens 3a is larger than a predetermined value, the focus lens 3a is focused. As a result, the AF frame can be easily moved and the live view display can be easily viewed.

  In S121 of FIG. 17, it is determined whether or not the release button 30 is fully pressed and SW2 is turned on. If it is turned on, the process proceeds to S122, and if it is not turned on, there is a possibility that the AF frame has been moved further. Considering this, the process proceeds to S120.

  In S122, a live view shooting routine is executed. FIG. 24 is a flowchart of the live view shooting routine. In S191, a so-called imaging surface AE operation is performed in which the memory controller 21 reads an image signal from the imaging device 6 and obtains the focused main subject and photometric information around it. In S192, the lens control circuit 23 drives a diaphragm (not shown) in the photographic lens 3 according to the photographic exposure calculated from the imaging surface AE result. In S193, the image received by the image pickup device 6 by the memory controller 21 is reset to return the light receiving state of the image pickup device 6 to the initial state, that is, the state where nothing is picked up. In S 194, the memory controller 21 receives light again from the image sensor 6, reads an image, and temporarily records it in the SDRAM 43. In S195, defective pixel interpolation of the image signal read by the memory controller 21 is performed. In S196, the image processing circuit 44 performs image processing such as white balance correction, γ correction, and edge enhancement, and the image compression / decompression circuit 45 compresses the image according to a format such as JPEG. In S 197, the captured image that has undergone image processing is recorded on the medium 48. In S198, the shutter 5 is closed by the shutter drive circuit 27. In S199, the motor drive circuit 26 controls a mirror drive motor (not shown) to mirror down the main mirror 4 and the sub mirror 7 (the state shown in FIG. 1 is obtained). In S200, the motor drive circuit 26 controls energization of a charging motor (not shown) to charge the shutter 5. Then, the process returns to S110 in the main routine of FIG.

  As described above, according to the present embodiment, since TV-AF is performed on the image in the AF frame based on the imaging surface phase difference AF result, AF is performed anywhere in the imaging area during live view. It is possible to realize AF with high focusing accuracy and fast focusing time. Further, by arranging the horizontal deviation detection pixels and the vertical deviation detection pixels in a checkered pattern at substantially equal intervals and equal density in the entire imaging region of the image pickup device 6, an object having a luminance distribution in the horizontal direction and a vertical direction are arranged. The imaging plane phase difference AF is possible for any subject having a luminance distribution. For this reason, even if the AF frame is moved to an arbitrary position in the imaging region by face recognition or the user, an imaging surface phase difference AF result can be obtained anywhere. In addition, since the focus detection pixels are discretely arranged, there is little loss of the imaging pixels, and deterioration of the captured image can be avoided.

  The present invention is applicable not only to digital single-lens reflex cameras but also to digital compact cameras, digital video cameras, various inspection digital cameras, surveillance digital cameras, endoscope digital cameras, digital cameras for robots, and the like. Moreover, arrangement | positioning, a numerical value, etc. of the component described in this embodiment are exemplary, and are not the meaning which limits the scope of the present invention only to them.

It is sectional drawing of the digital camera of the Example at the time of multi view and imaging | photography. It is sectional drawing of the digital camera of the Example at the time of finder observation. It is a block diagram of the control system of the digital camera shown in FIG. It is a figure explaining the structure of the pixel for an imaging used for the image sensor shown in FIG. 1, and the pixel for a focus detection. It is a figure explaining the structure of the pixel for an imaging used for the image sensor shown in FIG. 1, and the pixel for a focus detection. It is a figure explaining the structure of the pixel for an imaging used for the image sensor shown in FIG. 1, and the pixel for a focus detection. FIG. 2 is a pixel array explanatory diagram of a minimum unit of the image sensor shown in FIG. 1. FIG. 2 is an explanatory diagram of a pixel arrangement in the upper unit of the image sensor shown in FIG. 1. FIG. 2 is an explanatory diagram of a pixel arrangement in the entire area of the image sensor shown in FIG. 1. It is a pixel grouping method explanatory view at the time of lateral shift focus detection. It is an image sampling characteristic explanatory view at the time of lateral shift focus detection. It is explanatory drawing of the pixel grouping method at the time of longitudinal shift focus detection. It is image sampling characteristic explanatory drawing at the time of a longitudinal shift focus detection. It is a conceptual diagram explaining the pupil division | segmentation condition of the image pick-up element shown in FIG. It is AF operation explanatory drawing at the time of live view. FIG. 5 is a relationship diagram between a focus lens position and a contrast value for an image in an AF frame. 2 is a flowchart showing an operation of the digital camera shown in FIG. 18 is a flowchart for explaining details of a normal photographing routine S109 shown in FIG. It is a flowchart explaining the detail of live view display routine S111 shown in FIG. 18 is a flowchart illustrating details of an imaging surface phase difference AF routine S117 shown in FIG. It is a flowchart explaining the detail of contrast AF routine S118 shown in FIG. It is a flowchart explaining the detail of AF frame movement process routine S120 shown in FIG. FIG. 23 is a flowchart for describing details of an AF frame area imaging surface phase difference AF routine S175 shown in FIG. 22; FIG. It is a flowchart explaining the detail of live view imaging | photography routine S122 shown in FIG.

Explanation of symbols

3 Shooting Lens 6 Image Sensor 14 Liquid Crystal Monitor (Display Unit)
20 MPU (control unit)
33 Multi-controller (mode setting section, frame setting section)
43 SDRAM

Claims (10)

A mode setting section for setting the live view mode;
A plurality of shooting pixels each including light that passes through the entire exit pupil of an imaging lens that includes a focus lens and forms an image of the subject, and generates the image of the subject; and each of the exit pupils of the imaging lens A plurality of focus detection pixels that receive light passing through a partial area of the imaging lens, and the plurality of focus detection pixels as a whole receive light passing through the entire exit pupil of the photographing lens; ,
A position detector for detecting a current position of the focus lens of the photographing lens;
A frame setting unit that sets a focus detection frame that is a target of focus detection at an arbitrary position in the imaging region of the image sensor;
Defocus amount of the focus detection frame by performing focus detection by the phase difference detection method for the focus detection frame by calculating an output signal of the focus detection pixel of the focus detection frame set by the frame setting unit. The frame setting unit calculates a focus detection by a contrast detection method based on the in-focus position of the focus lens obtained from the defocus amount and the current position of the focus lens of the photographing lens detected by the position detection unit. A control unit for performing the set focus detection frame;
An imaging device comprising: The imaging device further includes a memory,
The imaging apparatus according to claim 1, wherein the control unit records an output signal of the focus detection pixels in the entire imaging area of the imaging element. The imaging device further includes a memory,
The control unit calculates and records a defocus amount by performing focus detection of a phase difference detection method by calculating an output signal of the focus detection pixel over the entire imaging region of the imaging element. The imaging apparatus according to claim 1.   When the mode setting unit sets the live view mode, the focus detection frame that can be set by the frame setting unit and the focus detection frame set by the frame setting unit while displaying the image of the subject captured by the imaging device. The image pickup apparatus according to claim 1, further comprising a display unit that displays the image.   The control unit, as the defocus amount, a value having the highest reliability among a plurality of defocus amounts calculated from a plurality of focus detection pixels arranged in the focus detection frame, the closest value, Alternatively, the imaging device according to claim 1, wherein an average value of the plurality of defocus amounts is selected. The imaging apparatus further includes a driver that drives the focus lens;
When the focus detection frame is moved after the driver has moved the focus lens to the in-focus position, the control unit reads out information on the focus detection pixels of the moved focus detection frame from the memory and shifts the focus. An amount is calculated, and focus detection of a contrast detection method is performed on the moved focus detection frame based on the focus shift obtained from the defocus and the current position of the focus lens. Item 4. The imaging device according to Item 2 or 3.   The imaging apparatus according to claim 6, wherein the moved focus detection frame is a focus detection frame in which the frame setting unit resets the focus detection frame.   The imaging apparatus according to claim 6, wherein the moved focus detection frame is a moving focus detection frame.   The image pickup apparatus according to claim 6, wherein the control unit follows the movement of the focus detection frame, and the driver moves the focus lens to a focus position.   10. The focus detection pixels include lateral shift detection pixels and vertical shift detection pixels arranged at equal intervals and at equal density throughout the imaging region of the image sensor. The imaging device according to any one of the above.