JP2015106057A - Focus detection device and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus detection device that enables any one of a subject image or a background to be focused on even when the subject image is smaller or larger with respect to the background.SOLUTION: A focus detection device comprises: focus detection means for computing a plurality of focus detection parameters by performing a focus detection for each division area of a plurality of division areas in a focus detection area, and determining a focus adjustment parameter out of the plurality of focus detection parameters; and subject image area discrimination means for discriminating a plurality of subject image areas which includes a prescribed area corresponding to the focus detection area and an imaging plane and corresponds to each of a plurality of subject images formed respectively in the prescribed area by an optical system in the prescribed area. When the plurality of subject image areas is discriminated in the prescribed area, the focus detection means is configured to determine the focus adjustment parameter out of the plurality of focus detection parameters computed as to the plurality of division areas corresponding to each of the plurality of subject image areas.

Description

  The present invention relates to a focus detection apparatus and an imaging apparatus.

  An imaging device that can focus on a subject by calculating the spatial frequency distribution of the entire region including the subject image and the region in the subject image and removing the frequency band corresponding to the background by filtering is disclosed. (For example, refer to Patent Document 1).

JP 2012-215700 A

  According to the imaging apparatus disclosed in Patent Document 1, for example, when the subject image is small with respect to the background, the influence of the background is large. Therefore, when performing filtering on the background in order to focus on the subject image In addition, it may be difficult to specify the frequency band corresponding to the background to be removed. In that case, there is a problem that the subject image cannot be focused.

(1) In the focus detection apparatus according to the first aspect, the focus detection is performed by the phase difference method for each of the plurality of divided areas in the focus detection area provided on the imaging surface of the optical system, thereby the plurality of focal points. A focus detection unit that calculates a detection parameter and determines a focus adjustment parameter used for focus adjustment from among a plurality of focus detection parameters, a focus detection region, and a predetermined region corresponding to the imaging plane, and an optical A plurality of subject image regions for determining a plurality of subject image regions corresponding to each of the plurality of subject images respectively formed in the predetermined region by the system, and the plurality of subjects by the subject image region determination unit. When the image area is determined within the predetermined area, the focus detection unit is configured to calculate a plurality of focal points calculated for a plurality of divided areas respectively corresponding to the plurality of subject image areas. From among the parameters for output, and determines the parameter for focus adjustment.
(2) An imaging device according to a seventh aspect receives the focus detection device according to any one of the first to sixth aspects, an optical system, and a light beam that has passed through the optical system, and outputs an imaging signal. When the optical system is focused on the light receiving surface of the image sensor by the image sensor, the focus adjuster that performs focus adjustment based on the focus detection performed by the focus detector, and is output by the image sensor. Image generating means for generating an image based on the captured image signal.

  According to the present invention, it is possible to focus on any one of the subject image and the background desired by the user.

It is a figure which shows the structure of the imaging device containing the focus detection apparatus in one embodiment of this invention. It is a figure which shows the correspondence of the focus detection area in an imaging | photography screen, the focus detection pixel row | line | column on a focus detection sensor, and the to-be-recognized area | region on a photometry sensor. It is a figure for demonstrating the correspondence of a focus detection area | region, a focus detection pixel row | line | column, and a to-be-recognized area. It is a flowchart of the focus detection process performed by a control apparatus. It is a figure which shows an example in which two subject images are included in the focus detection area. It is a figure for demonstrating the discrimination | determination process of two object image areas, and the determination process of the defocus amount for focus adjustment. It is a figure for demonstrating the discrimination | determination process of two object image areas, and the determination process of the defocus amount for focus adjustment. It is a flowchart of the imaging process performed by a control apparatus. FIG. 6 is a diagram illustrating an example in which three subject images are included in a focus detection area, and a diagram for explaining a focus adjustment defocus amount determination process.

  A focus detection apparatus and an imaging apparatus including the focus detection apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of an imaging apparatus 100 including a focus detection apparatus 50 according to the present embodiment. The imaging device 100 includes a focus detection device 50, a photographing optical system 1, a half mirror 2, a finder screen 3, a pentaprism 4, an eyepiece lens 5, an imaging element 6, a sub mirror 7, and a focus adjustment device 13. A lens driving motor 14, a photometric lens 15, a photometric sensor 16, an operation member 17, and a storage device 19. The focus detection device 50 includes a focus detection sensor 8, a re-imaging optical system 9, and a control device 18. In the focus detection device 50, a focal point that receives a pair of light beams that have passed through a pair of pupil regions of the photographing optical system 1 via a re-imaging optical system 9 configured by arranging a plurality of pairs of re-imaging lenses. The control device 18 performs focus detection processing of the photographing optical system 1 by a pupil division type phase difference detection method using a pair of focus detection signals output by the detection sensor 8.

  The photographing optical system 1 is an optical system for forming a subject image on an imaging surface. The photographing optical system 1 includes a plurality of lenses and diaphragms, and a focus adjustment lens among the plurality of lenses can be moved in the direction of the optical axis 10 of the photographing optical system 1 by a lens driving motor 14.

  In the focus detection process, the half mirror 2 is positioned in the optical path along the optical axis 10 as shown in FIG. 1, and a part of the incident light beam that has passed through the photographing optical system 1 is separated by the finder screen 3 and the pentaprism 4. Reflects in the direction in which it is located and transmits the remaining unreflected light of the incident light flux. The light that has passed through the half mirror 2 is reflected by the sub-mirror 7, divided into pupils when passing through the re-imaging optical system 9 constituted by the re-imaging lens, and passed through a pair of pupil regions of the imaging optical system 1. The light enters the focus detection sensor 8 as a pair of light beams. An imaging surface 20c on which a subject image is formed by the photographing optical system 1 is formed on the finder screen 3, and an imaging surface 20b on which the subject image is formed by the photographing optical system 1 is a re-imaging optical system. 9 is formed above.

  A plurality of pairs of focus detection pixel rows are arranged in the focus detection sensor 8. A plurality of focus detection pixels are arranged in each of the pair of focus detection pixel columns, and the plurality of focus detection pixels receive a pair of light beams incident on the focus detection sensor 8 and perform photoelectric conversion processing, thereby performing a connection. A plurality of electrical focus detection signals corresponding to the subject image formed on the image plane 20b are generated. Therefore, a pair of focus detection signal strings is generated by the pair of focus detection pixel strings. The focus detection sensor 8 outputs a plurality of pairs of focus detection signal sequences generated by the plurality of pairs of focus detection pixel sequences. When a pair of focus detection signal sequences are generated by a pair of focus detection pixel sequences, for example, exposure control of a plurality of focus detection pixels, readout control of a plurality of focus detection signals, and / or photoelectric conversion control of the focus detection sensor 8 Alternatively, the control device 18 performs amplification control of the plurality of read focus detection signals.

  The control device 18 detects the focus of the photographing optical system 1 by detecting the phase difference amount of the pair of focus detection signal sequences output by the focus detection sensor 8. The control device 18 transmits the lens driving amount of the photographing optical system 1 corresponding to the defocus amount obtained as a result of the focus detection to the focus adjusting device 13, and photographing to the focus adjusting device 13 via the lens driving motor 14. The lens of the optical system 1 is driven. Details of the focus detection processing performed by the control device 18 will be described later with reference to FIG.

  During the photographing process, the half mirror 2 together with the sub mirror 7 jumps up so as to block the finder screen 3 and retreats from the optical path, so that the incident light flux that has passed through the photographing optical system 1 enters the image sensor 6 and takes an image. A subject image is formed on the imaging surface 20 a on the element 6. The imaging element 6 has a plurality of imaging pixels arranged in a two-dimensional manner. The plurality of imaging pixels receive the incident light flux and perform photoelectric conversion, whereby the imaging optical system 1 connects the imaging surface 20a. A plurality of electrical imaging signals corresponding to the imaged subject image are generated. The plurality of generated imaging signals are output by the imaging device 6. Although not shown, an infrared cut filter for cutting infrared light and an optical low-pass filter for preventing image aliasing noise are usually arranged on the light receiving surface of the image sensor 6.

  The control device 18 generates an image based on the plurality of imaging signals output by the imaging element 6 and records the generated image in the storage device 19. Details of the imaging processing performed by the control device 18 will be described later with reference to FIG.

  As described above, a part of the incident light beam that has passed through the photographing optical system 1 is reflected by the half mirror 2 in the direction in which the finder screen 3 and the pentaprism 4 are located. The light that has entered the pentaprism 4 passes through the photometric lens 15 and enters the photometric sensor 16, or passes through the eyepiece lens 5 and reaches the eyes of the user who looks into the imaging device 100. As described above, since the imaging surface 20c on which the subject image is formed by the imaging optical system 1 is formed on the finder screen 3, the imaging screen including the subject image formed on the imaging surface 20c is included. 20 is reflected in the eyes of the user looking into the imaging apparatus 100.

  A plurality of photometric pixels are two-dimensionally arranged on the photometric sensor 16. The plurality of photometric pixels generate a plurality of electrical photometric signals corresponding to the subject image formed on the imaging surface 20c by receiving a light beam incident on the photometric sensor 16 and performing a photoelectric conversion process. . A plurality of photometric signals generated as color image signals are output to the control device 18 by the photometric sensor 16, so that the control device 18 can determine the subject image region in the subject image recognition region on the photometric sensor 16. .

  The focus adjustment device 13 drives the lens driving motor 14 to move the lens of the photographing optical system 1 by the lens driving amount obtained by the control device 18 performing focus detection of the photographing optical system 1.

  The operation member 17 is a member for the user to input various commands such as a command for specifying a focus detection area and an imaging instruction command to the control device 18.

  FIG. 2 is a diagram illustrating a correspondence relationship between the focus detection area in the photographing screen 20, the focus detection pixel array on the focus detection sensor, and the subject recognition area on the photometry sensor. FIG. 2A shows an example in which eleven focus detection areas 200 are provided on the photographing screen 20. The imaging screen 20 is equivalent to any of the imaging surfaces 20a, 20b, and 20c shown in FIG. The shooting screen 20 includes a focus detection area 200 where the focus detection described above is performed. The control device 18 performs focus detection of the photographing optical system 1 based on a pair of focus detection signal sequences corresponding to the focus detection region 200.

  FIG. 2B is a diagram showing four focus detection visual fields 81, 82, 83, and 84 formed on the imaging surface 20b and four pairs of focus detection pixel columns corresponding to the focus detection visual fields 81, 82, 83, and 84, respectively. The four focus detection fields 81, 82, 83, and 84 include two vertical focus detection fields 81 and 82 and two horizontal focus detection fields 83 and 84. Each of the four focus detection fields 81, 82, 83, and 84 is obtained by projecting a corresponding pair of focus detection pixel columns so as to overlap each other. It should be noted that four pairs of focus detection pixel rows 81a and 81b, 82a and 82b, 83a and 83b, in which four pairs of focus detection signal rows corresponding to the four focus detection fields 81, 82, 83, and 84, respectively, are generated. , And 84a and 84b, line sensors are assumed here, but a staggered lattice arrangement in which adjacent focus detection pixels are shifted from each other by half a pixel may be applied.

  The light beam that has passed through the focus detection visual field 81 extending in the vertical direction of the imaging surface 20 b is divided into pupils by the re-imaging optical system 9. A pair of light fluxes obtained by pupil division is paired with a pair of vertical focus detection pixels on the focus detection sensor 8 via a pair of vertical re-imaging lenses 95a and 95b constituting the re-imaging optical system 9, respectively. Light is received by the columns 81a and 81b, and a pair of focus detection signal sequences is generated. In other words, the pair of vertical focus detection pixel rows 81a and 81b are projected on the same vertical focus detection field 81 through the pair of vertical re-imaging lenses 95a and 95b. . The plurality of focus detection pixels 810a and 810b that respectively constitute the pair of vertical focus detection pixel rows 81a and 81b are also illustrated as a plurality of focus detection pixel projection images 810 that overlap each other in the focus detection field 81.

  The light beam that has passed through the focus detection visual field 82 extending in the vertical direction of the imaging surface 20 b is divided into pupils by the re-imaging optical system 9. A pair of light fluxes obtained by pupil division is paired with a pair of vertical focus detection pixels on the focus detection sensor 8 via a pair of vertical re-imaging lenses 95a and 95b constituting the re-imaging optical system 9, respectively. Light is received by the columns 82a and 82b, and a pair of focus detection signal sequences is generated. In other words, the pair of vertical focus detection pixel rows 82a and 82b are connected to the same vertical focus through a pair of vertical re-imaging lenses 95a and 95b constituting the re-imaging optical system 9. The projection is superimposed on the detection field 82. A plurality of focus detection pixels 820a and 820b that respectively constitute a pair of vertical focus detection pixel rows 82a and 82b are also illustrated as a plurality of focus detection pixel projection images 820 that overlap each other in the focus detection field 82.

  The light beam that has passed through the focus detection visual field 83 extending in the horizontal direction on the imaging surface 20b is pupil-divided by the re-imaging optical system 9. A pair of light fluxes obtained by the pupil division are paired with a pair of horizontal focus detection pixels on the focus detection sensor 8 via a pair of horizontal reimage lenses 96a and 96b constituting the reimaging optical system 9, respectively. Light is received by the columns 83a and 83b, and a pair of focus detection signal sequences is generated. In other words, the pair of horizontal focus detection pixel rows 83a and 83b are connected to the same horizontal focus through a pair of horizontal re-imaging lenses 96a and 96b constituting the re-imaging optical system 9. The projection is superimposed on the detection field 83. The plurality of focus detection pixels 830a and 830b that respectively constitute the pair of horizontal focus detection pixel rows 83a and 83b are also illustrated as a plurality of focus detection pixel projection images 830 that overlap each other in the focus detection field 83.

  The light beam that has passed through the focus detection visual field 84 extending in the horizontal direction of the imaging surface 20b is divided into pupils by the re-imaging optical system 9. A pair of light fluxes obtained by the pupil division are paired with a pair of horizontal focus detection pixels on the focus detection sensor 8 via a pair of horizontal reimage lenses 96a and 96b constituting the reimaging optical system 9, respectively. Light is received by the columns 84a and 84b, and a pair of focus detection signal sequences is generated. In other words, the pair of horizontal focus detection pixel rows 84a and 84b are connected to the same horizontal focus through the pair of horizontal re-imaging lenses 96a and 96b constituting the re-imaging optical system 9. The projection is superimposed on the detection field 84. The plurality of focus detection pixels 840a and 840b that respectively constitute the pair of horizontal focus detection pixel rows 84a and 84b are also illustrated as a plurality of focus detection pixel projection images 840 that overlap each other in the focus detection field 84.

  FIG. 2C shows a state in which the four focus detection visual fields 81, 82, 83 and 84 corresponding to the four pairs of focus detection signal sequences described above are formed on the image plane 20b, and the four focus points. A state in which the focus detection areas 200 corresponding to the detection visual fields 81, 82, 83, and 84 are superimposed on the imaging surface 20b is shown.

  FIG. 2D is a diagram in which the photometric sensor 16 in which a plurality of photometric pixels 160 are two-dimensionally arranged is superimposed on the imaging screen 20 representing the eleven focus detection areas 200. Each focus detection region 200 corresponds to a plurality of photometric pixels 160 arranged in a part of the photometric sensor 16.

  FIG. 3 is a diagram for explaining a correspondence relationship between the focus detection area 200, the focus detection pixel array, and the subject recognition area 161. FIG. 3A is a diagram showing a correspondence relationship between the focus detection area 200 and the four focus detection fields 81, 82, 83, and 84. FIG. As shown in FIG. 2B, the vertical focus detection field 81 has a pair of vertical focus detection pixel rows 81a and 81b formed by the re-imaging lenses 95 (a) and 95 (b). It is obtained by projecting to 20b. In FIG. 3 (a), a plurality of focus detection pixels 810a and 810b constituting a pair of vertical focus detection pixel rows 81a and 81b are formed into an image plane by re-imaging lenses 95 (a) and 95 (b), respectively. A plurality of focus detection pixel projection images 810 that are projected onto 20 b and overlap each other are shown in the focus detection field 81. The vertical focus detection visual field 82 is obtained by projecting a pair of vertical focus detection pixel rows 82a and 82b onto the image plane 20b by the re-imaging lenses 95 (a) and 95 (b). In FIG. 3 (a), a plurality of focus detection pixels 820a and 820b constituting a pair of vertical focus detection pixel rows 82a and 82b, respectively, are imaged by re-imaging lenses 95 (a) and 95 (b). A plurality of focus detection pixel projection images 820 projected onto 20b and overlapped with each other are shown in the focus detection field 82.

  The horizontal focus detection visual field 83 is obtained by projecting a pair of horizontal focus detection pixel rows 83a and 83b onto the imaging surface 20b by the re-imaging lenses 96 (a) and 96 (b). In FIG. 3A, a plurality of focus detection pixels 830a and 830b constituting a pair of horizontal focus detection pixel rows 83a and 83b, respectively, are imaged by re-imaging lenses 96 (a) and 96 (b). A plurality of focus detection pixel projection images 830 that are projected onto 20 b and overlap each other are shown in the focus detection field 83. The horizontal focus detection field 84 is obtained by projecting a pair of horizontal focus detection pixel rows 84a and 84b onto the imaging surface 20b by the re-imaging lenses 96 (a) and 96 (b). In FIG. 3 (a), a plurality of focus detection pixels 840a and 840b constituting a pair of horizontal focus detection pixel rows 84a and 84b, respectively, are imaged by re-imaging lenses 96 (a) and 96 (b). A plurality of focus detection pixel projection images 840 that are projected onto 20 b and overlap each other are shown in the focus detection field of view 84.

  Of the four focus detection fields 81, 82, 83, and 84 shown in FIG. 3A, two focus detection fields 81 and 82 in the vertical direction are shown in FIG. FIG. 3C shows vertical divided areas 210 and 220 of the focus detection area 200 capable of focus detection corresponding to 81 and 82. A divided area 210 shown in FIG. 3C is an area extending in a predetermined vertical direction on the left side from the center of the focus detection area 200 shown in FIG. A divided region 220 shown in FIG. 3C is a region extending in a predetermined vertical direction on the right side from the center of the focus detection area 200 shown in FIG.

  Since the focus detection visual field 81 corresponds to the pair of focus detection pixel rows 81a and 81b shown in FIG. 2B, the focus detection pixel row 81a is configured in FIG. 3B as in FIG. 2B. The focus detection field 81 includes a plurality of focus detection pixel projection images 810 in which a plurality of focus detection pixels 810a and a plurality of focus detection pixels 810b constituting the focus detection pixel array 81b are projected to overlap each other. The focus detection in the vertical divided region 210 by the control device 18 is performed using a pair of focus detection signal sequences generated by the pair of focus detection pixel columns 81a and 81b corresponding to the focus detection visual field 81. Since the focus detection visual field 82 corresponds to the pair of focus detection pixel rows 82a and 82b shown in FIG. 2B, the focus detection pixel row 82a is configured in FIG. 3B as in FIG. 2B. The focus detection field 82 includes a plurality of focus detection pixel projection images 820 in which a plurality of focus detection pixels 820a and a plurality of focus detection pixels 820b constituting the focus detection pixel row 82b are projected to overlap each other. The focus detection in the vertical divided region 220 by the control device 18 is performed using a pair of focus detection signal sequences generated by the pair of focus detection pixel rows 82a and 82b corresponding to the focus detection visual field 82.

  Of the four focus detection fields 81, 82, 83, and 84 shown in FIG. 3 (a), two focus detection fields 83 and 84 in the horizontal direction are shown in FIG. FIG. 3E shows horizontal divided areas 230 and 240 of the focus detection area 200 capable of focus detection corresponding to 83 and 84. A divided area 230 shown in FIG. 3E is an area extending in a predetermined horizontal direction above the center of the focus detection area 200 shown in FIG. The divided region 240 shown in FIG. 3E is a region extending in the horizontal direction that is predetermined below the center of the focus detection area 200 shown in FIG.

  Since the focus detection visual field 83 corresponds to the pair of focus detection pixel rows 83a and 83b shown in FIG. 2B, the focus detection pixel row 83a is configured in FIG. 3D as in FIG. 2B. The focus detection visual field 83 includes a plurality of focus detection pixel projection images 830 in which a plurality of focus detection pixels 830a and a plurality of focus detection pixels 830b constituting the focus detection signal sequence 83b are projected to overlap each other. The focus detection in the horizontal divided region 230 by the control device 18 is performed using a pair of focus detection signal sequences generated by the pair of focus detection pixel rows 83a and 83b corresponding to the focus detection visual field 83. Since the focus detection visual field 84 corresponds to the pair of focus detection pixel rows 84a and 84b shown in FIG. 2B, the focus detection pixel row 84a is configured in FIG. 3D as in FIG. 2B. The focus detection visual field 84 includes a plurality of focus detection pixel projection images 840 in which a plurality of focus detection pixels 840a and a plurality of focus detection pixels 840b constituting the focus detection pixel row 84b are projected to overlap each other. The focus detection in the horizontal divided region 240 by the control device 18 is performed using a pair of focus detection signal sequences generated by the pair of focus detection pixel rows 84a and 84b corresponding to the focus detection visual field 84.

  The main subject to be focused is any one of the divided areas 210, 220, 230, and 240 predetermined in the focus detection area 200 shown in FIGS. 3 (c) and 3 (e). When located in a divided area, a pair of focus detection signal sequences or a pair corresponding to any one of the four focus detection fields 81, 82, 83 and 84 corresponding to the divided area where the main subject is located. Using the phase difference amount and / or the defocus amount of the partial signal sequence, focus detection for focusing on the main subject is performed. An example will be described later with reference to FIGS.

  FIG. 3F is an enlarged view of FIG. 2D, in which a photometric sensor 16 in which a plurality of photometric pixels 160 are two-dimensionally arranged is projected onto the photographing screen 20, and focus detection is performed. FIG. 6 is a diagram showing a subject recognition area 161 that includes a focus detection area 200 by overlapping the areas 200; The subject recognition area 161 includes, for example, four pixels in the horizontal direction × 4 pixels in the vertical direction, that is, a total of 16 photometric pixels 160.

  FIG. 4 is a flowchart of the focus detection process performed by the control device 18. The control device 18 is a computer configured with, for example, a CPU and a memory. When the CPU executes the computer program stored in the memory, the process of each step constituting the focus detection process shown in FIG. 4 is performed.

  The process of each step constituting the focus detection process shown in FIG. 4 will be described using the example of the photographing screen 200 shown in FIG. FIG. 5 is a diagram illustrating an example in which two subject images 68 and 69 are included in one focus detection region 200 in the photographing screen 20. In FIG. 5, the photographing screen 200 includes two subject images formed by the photographing optical system 1, that is, a subject image 68 of a main subject and a background subject image 69 including a tree. Although the eleven focus detection areas 200 shown in FIG. 2A are also displayed on the photographing screen 200, the photographing screen 200 in FIG. 5 is designated by the user in step S101 in FIG. Only one focus detection area 200 is illustrated. The designated focus detection area 200 also includes a subject image 68 of a main subject located near the imaging device 100 and a background subject image 69 including a tree located far from the imaging device 100. Yes.

  In step S101 of FIG. 4, the control device 18 starts the focus detection process by the user via the operation member 17 and also selects one focus detection area from among the 11 focus detection areas 200 illustrated in FIG. 2. 200 is determined by the user via the operation member 17. In the case of negative determination, the process of step S101 is repeated until an affirmative determination is made. In the case of an affirmative determination, the control device 18 advances the process for the designated focus detection area 200 to step S102. The operation member 17 is, for example, an automatic focus detection activation switch, and this process is started when the automatic focus detection activation switch is set to ON. Alternatively, the operation member 17 is a shutter release button, and this processing is started when the shutter release button is set to a half-pressed state.

  In step S <b> 102, the control device 18 performs photoelectric conversion control of the focus detection sensor 8. As the photoelectric conversion control of the focus detection sensor 8, for example, exposure control of a plurality of focus detection pixels arranged in the focus detection sensor 8, readout control of a plurality of focus detection signals, and / or readout of a plurality of focus detection signals. Amplification control and the like are performed.

  In step S103, the control device 18 acquires a plurality of pairs of focus detection signal sequences based on the plurality of focus detection signals read in step S102. According to the example shown in FIG. 2B, four pairs of focus detection signal strings, that is, a pair of focus detection signal strings generated by the pair of focus detection pixel strings 81a and 81b, and a pair of focus detection pixel strings. A pair of focus detection signal sequences generated by the pair of focus detection pixel rows 83a and 82b, a pair of focus detection signal sequences generated by the pair of focus detection pixel rows 83a and 83b, and a pair of focus detection pixel rows 84a and 84b. Are obtained.

  In step S <b> 104, the control device 18 sets a subject recognition area 161 on the photometric sensor 16. The subject recognition area 161 includes, for example, a total of 16 photometric pixels 160 of 4 pixels in the horizontal direction and 4 pixels in the vertical direction as shown in FIG.

  In step S105, the control device 18 sets a search area including the subject recognition area 161 on the photometric sensor 16, and measures the hue value of each hue and the luminance value of the luminance in each photometric pixel 160 within the search area. To do. The control device 18 determines the subject image in the search area depending on whether the difference in hue value between the photometric pixels 160 is larger than a predetermined threshold and whether the difference in luminance value is larger than a predetermined threshold. Determine the area. For example, the main subject image area and the background image area in the search area are determined. Note that the processing in steps S104 and S105 may not be performed after the processing in steps S102 and S103. For example, it may be performed in parallel with the processing of steps S102 and S103.

  In step S106, the control device 18 determines whether or not a plurality of subject images are included in the search area. For example, when the search area includes a background image far away from the imaging device 100 and a main subject image closer thereto, an affirmative determination is made, and the control device 18 advances the process to step S107. When a negative determination is made, the control device 18 advances the process to step S115.

  In step S <b> 107, the control device 18 specifies a plurality of divided regions respectively corresponding to the plurality of subject images in the focus detection region 200. In the case of the example illustrated in FIG. 5, the control device 18 specifies two divided regions corresponding to the plurality of subject images 68 and 69, respectively. Details will be described later with reference to FIGS. 6 and 7.

  In step S108, the control device 18 calculates the phase difference amount of each pair of the plurality of pairs of focus detection signal sequences obtained in step S103. The plurality of phase difference amounts corresponding to each of the plurality of pairs of focus detection signal sequences calculated in this way is a kind of focus detection parameter. Therefore, although it is possible to perform the processing after step S109 based on the plurality of phase difference amounts, the control device 18 further calculates a plurality of defocus amounts based on the plurality of phase difference amounts. A plurality of defocus amounts corresponding to each of a plurality of pairs of focus detection signal sequences is also a kind of focus detection parameter.

  In step S109, the control device 18 determines the closest defocus amount among the plurality of defocus amounts calculated in step S108 as the defocus amount for focus adjustment. Since the focus position of the photographic optical system 1 with respect to the subject closest to the imaging apparatus 100 is located at the position farthest from the photographic optical system 1, the defocus amount on the closest side is specified. Of the plurality of defocus amounts calculated in step S108, the defocus amount corresponding to the subject image 68 of the main subject which is a nearby subject is the closest defocus amount.

  In step S115 performed when a negative determination is made in step S106, since the focus detection area 200 includes only one subject image, the control device 18 acquires a plurality of pairs of focus detection signals acquired in step S103. The phase difference amount of any one pair of focus detection signal sequences in the sequence is calculated. The control device 18 calculates one defocus amount based on the calculated phase difference amount, and determines the defocus amount as the focus adjustment defocus amount.

  In step S110, the control device 18 determines whether or not the photographing optical system 1 is at the in-focus position based on whether or not the focus adjustment defocus amount determined in step S109 or S115 is substantially zero. To do. If the determination is affirmative, this process ends. If the determination is negative, the process proceeds to step S111.

  In step S111, the control device 18 calculates the lens driving amount of the photographing optical system 1 based on the defocus amount for focus adjustment determined in step S109 or S115.

  In step S112, the control device 18 transmits the lens driving amount calculated in step S111 to the focus adjusting device 13, and causes the focus adjusting device 13 to drive the lens of the photographing optical system 1 via the lens driving motor 14. Thus, the focus adjustment device 13 is controlled. When the process of step S112 is completed, the process returns to step S101.

  Based on the example shown in FIG. 5, the focus detection processing by the control device 18 shown in FIG. 4 will be described with reference to FIGS. 6 and 7. FIG. 6 is a diagram for explaining the determination processing of the two subject image areas in step S105 of FIG. 4 and the determination processing of the defocus amount for focus adjustment performed through steps S107, S108, and S109. FIG. 6A shows a focus detection area 200 shown as an example in FIG. 5 on a photographing screen 20 in which a search area 162 including a subject recognition area 161 on a photometric sensor 16 in which a plurality of photometric pixels 160 are arranged is projected. FIG. The search area 162 includes a subject recognition area 161 of 4 pixels in the horizontal direction × 4 pixels in the vertical direction as shown in FIG. 3F as an example, and two pixels vertically and horizontally with respect to the subject recognition area 161. This is an expanded area.

  The reason why the search area 162 having a larger number of photometric pixels 160 is set because it is larger than the subject recognition area 161 is because, for example, the following two possibilities are considered. One possibility is that the focus detection area 200 specified by the user in step S101 in FIG. 4 includes only a part of the subject image 68 of the main subject, and therefore within the subject recognition area 161. It is considered that the main subject image area and the background image area cannot be distinguished. Another possibility is that the size of the subject image 68 of the main subject is larger than the size of the focus detection region 200, so that a characteristic portion (for example, an eye) of the main subject image is within the subject recognition region 161. It is conceivable that the main subject image area and the background image area cannot be distinguished.

  6A, the subject image 68 of the main subject is included in the right half of the focus detection area 200 toward the paper surface, and the background subject image 69 including a tree is included in the left half of the focus detection region 200 toward the paper surface. include. In order to make the drawing easier to see, in the search area 162 of FIG. 6A, the clear illustration of the background subject image 69 including the tree is omitted, and the region other than the main subject image 68 is set as the background subject including the tree. Assume that image 69 occupies.

  FIG. 6B is a diagram showing a subject image region 680 including a subject image 68 of the main subject in the search region 162 and a subject image region 690 including a background subject image 69 including a tree. The subject image area 680 is hatched. In order to make the drawing easy to see, it is assumed that the subject image region 690 is not clearly shown in the search region 162 in FIG. 6B and the region other than the subject image region 680 is occupied by the subject image region 690. In step S105 in FIG. 4, the subject image areas 680 and 690 in FIG. 6B are determined.

  FIG. 6C shows a subject image 68 of the main subject shown in FIGS. 6A and 6B and a background subject including trees on the imaging plane 20b (see FIG. 1) corresponding to the shooting screen 20. An image 69, a focus detection area 200, four focus detection fields 81, 82, 83, and 84 corresponding to the focus detection area 200 shown in FIG. 3A, and four focus detection fields 81, 82, 83, and 8 is a diagram in which a plurality of focus detection pixel projection images 810, 820, 830, and 840 respectively corresponding to 84 are superimposed. In order to make the drawing easy to see, the background subject image 69 including the tree is not clearly shown in FIG. 6C, and the background subject image 69 including the tree occupies the area other than the subject image 68 of the main subject. It shall be. In FIG. 6C, the plurality of focus detection pixel projection images 810, 820, 830, and 840 corresponding to the subject images 68 and 69, respectively, have a plurality of focus detections as described with reference to FIG. It corresponds to pixels 810a and 810b, 820a and 820b, 830a and 830b, and 840a and 840b. A plurality of focus detection pixels 810a and 810b, 820a and 820b, 830a and 830b, and 840a and 840b respectively corresponding to the subject image areas 680 and 690 in the photometric sensor 16 determined in FIG. Is identified by referring to a correspondence table stored in advance in the control device 18 or the storage device 19. A plurality of focus detection pixel projection images 810, 820, 830, and 840 corresponding to the identified plurality of focus detection pixels 810a and 810b, 820a and 820b, 830a and 830b, and 840a and 840b, respectively, are shown in FIG. 6 (d). .

  FIG. 6D shows a plurality of focus detection pixel projection images 820, 830 and 840 corresponding to the subject image region 680 by hatching. In order to make the drawing easy to see, in FIG. 6D, a plurality of focus detection pixel projection images 810, 820, 830 and 840 corresponding to the subject image region 690 are shown without hatching, and regions other than the subject image region 680 are shown. Assume that the subject image area 690 occupies. As shown in FIG. 6D, the vertical focus detection visual field 81 includes only a non-hatched area 812 corresponding to the subject image area 690. The focus detection visual field 82 in the vertical direction includes only a hatched area 821 that substantially corresponds to the subject image area 680, and includes only a small area 822 that does not correspond to the subject image area 690. The horizontal focus detection visual field 83 includes a hatched region 831 corresponding to the subject image region 680 and an unhatched region 832 corresponding to the subject image region 690. The horizontal focus detection visual field 84 includes a hatched area 841 corresponding to the subject image area 680 and an unhatched area 842 corresponding to the subject image area 690.

  As described with reference to FIG. 3A, there are four pairs of focus detection signal sequences respectively corresponding to the focus detection visual fields 81, 82, 83, and 84. In step S103 of FIG. Are obtained. In the example shown in FIG. 6D, the divided region 220 (see FIG. 3C) corresponding to the focus detection visual field 82 including the hatched region 821 and the focus detection visual field 83 including the hatched region 831. And a control unit in each of the divided areas 230 (see FIG. 3C) corresponding to, and the divided areas 240 (see FIG. 3C) corresponding to the focus detection visual field 84 including the hatched area 841. By performing the focus detection by 18, a plurality of focus detection parameters corresponding to the subject image region 680 can be calculated. In the example shown in FIG. 6D, the divided area 210 (see FIG. 3C) corresponding to the focus detection visual field 81 including the non-hatched area 812 and the focus detection including the non-hatched area 832. Each of the divided regions 230 (see FIG. 3C) corresponding to the visual field 83 and the divided regions 240 (see FIG. 3C) corresponding to the focus detection visual field 84 including the unhatched region 842. Thus, the focus detection by the control device 18 is performed, whereby a plurality of focus detection parameters corresponding to the subject image area 690 can be calculated.

  In other words, four focus detection parameters are calculated by performing focus detection in each of the four divided areas 210, 220, 230, and 240, and the focus detection parameters calculated in the divided areas 210 are trees. The focus detection parameter calculated in the divided region 220 corresponds to the subject image region 680 including the subject image 68 of the main subject. The two focus detection parameters calculated at 240 correspond to both the subject image areas 680 and 690.

  In the calculation of the focus detection parameter in step S108 of FIG. 4, for example, the phase difference amount of a pair of vertical focus detection signal sequences corresponding to the vertical focus detection field 81 and the vertical focus detection field 82 are supported. Two focus detection defocus amounts are calculated based on the phase difference amount of the pair of vertical focus detection signal sequences. In step S109 of FIG. 4, the closest defocus amount of the two focus detection defocus amounts is determined as the focus adjustment defocus amount. As described above, the focus detection visual field 81 corresponds to the divided region 210, and the defocus amount calculated in the divided region 210 corresponds to the subject image region 690 including the far-away background subject image 69 including the tree. The focus detection visual field 82 corresponds to the divided region 220, and the defocus amount calculated in the divided region 220 corresponds to the subject image region 680 including the subject image 68 of the nearby main subject. The defocus amount calculated based on the phase difference amount of the pair of focus detection signal sequences corresponding to the focus detection field 82 is the closest defocus amount, and is determined as the focus adjustment defocus amount.

  In the calculation of the focus detection parameter in step S108 of FIG. 4, for example, the focus detection defocus amount is calculated based on the phase difference amount of a pair of vertical focus detection signal sequences corresponding to the horizontal focus detection visual field 83. Instead, the control device 18 converts the pair of focus detection signal sequences into a pair of partial signal sequences corresponding to the hatched region 831 and a pair of partial signal sequences corresponding to the non-hatched region 832. It may be divided. In that case, based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 831 and the phase difference amount of the pair of partial signal sequences corresponding to the non-hatched region 832, two focus detection data The focus amount is calculated by the control device 18. A hatched region 831 corresponds to a subject image region 680 including a subject image 68 of a nearby main subject, and an unhatched region 832 corresponds to a subject image region 690 including a distant background subject image 69 including a tree. . Therefore, the focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 831 is the closest defocus amount, and is controlled as the focus adjustment defocus amount. Determined by device 18.

  In the calculation of the focus detection parameter in step S108 of FIG. 4, for example, the focus detection defocus amount is calculated based on the phase difference amount of the pair of vertical focus detection signal sequences corresponding to the horizontal focus detection visual field 84. Instead, the control device 18 converts the pair of focus detection signal sequences into a pair of partial signal sequences corresponding to the hatched region 841 and a pair of partial signal sequences corresponding to the non-hatched region 842. It may be divided. In that case, based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 841 and the phase difference amount of the pair of partial signal sequences corresponding to the non-hatched region 842, two focus detection data The focus amount is calculated by the control device 18. A hatched area 841 corresponds to a subject image area 680 including a subject image 68 of a nearby main subject, and an unhatched area 842 corresponds to a subject image area 690 including a distant background subject image 69 including a tree. . Therefore, the focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 841 is the closest defocus amount, and is controlled as the focus adjustment defocus amount. Determined by device 18.

  FIG. 7 is a diagram for explaining the determination processing of the two subject image areas in step S105 of FIG. 4 and the determination processing of the defocus amount for focus adjustment performed through steps S107, S108, and S109, as in FIG. It is. FIG. 7A shows focus detection in another example different from that shown in FIG. 5 on a photographing screen 20 in which a search area 162 including a subject recognition area 161 on a photometric sensor 16 in which a plurality of photometric pixels 160 are arranged is projected. It is the figure which overlap | superposed the area | region 200. FIG. Similar to FIG. 6, the search area 162 includes a subject recognition area 161 of 4 pixels in the horizontal direction × 4 pixels in the vertical direction as shown in FIG. 3F, and is located above and below the subject recognition area 161. This is an area expanded by two pixels to the left and right. In FIG. 7A, a subject image 68 of the main subject is included near the center of the focus detection area 200, and a background subject image 69 including trees is included on the right and left sides of the subject image 68 of the main subject toward the paper surface. It is. In order to make the drawing easy to see, in the search area 162 of FIG. 7A, the clear illustration of the background subject image 69 including the tree is omitted, and the area other than the main subject image 68 is set as the background subject including the tree. Assume that image 69 occupies.

  FIG. 7B is a diagram showing a subject image region 680 including a subject image 68 of a main subject in a search region 162 and a subject image region 690 including a background subject image 69 including a tree. The subject image area 680 is hatched. In order to make the drawing easy to see, it is assumed that the subject image region 690 is not clearly shown in the search region 162 in FIG. 7B and the region other than the subject image region 680 is occupied by the subject image region 690. In step S105 in FIG. 4, the subject image areas 680 and 690 in FIG. 7B are determined.

  FIG. 7C shows a subject image area 680 corresponding to the subject image 68 of the main subject in FIGS. 7A and 7B on the imaging surface 20b (see FIG. 1) corresponding to the shooting screen 20. The subject image area 690 corresponding to the background subject image 69 including the tree, the focus detection area 200, and the four focus detection visual fields 81, 82, 83 corresponding to the focus detection area 200 shown in FIG. 84 and a plurality of focus detection pixel projection images 810, 820, 830, and 840 corresponding to four focus detection fields of view 81, 82, 83, and 84, respectively. In order to make the drawing easier to see, the background subject image 69 including the tree is not clearly shown in FIG. 7C, and the background subject image 69 including the tree occupies the area other than the subject image 68 of the main subject. It shall be. In FIG. 7C, the plurality of focus detection pixel projection images 810, 820, 830, and 840 corresponding to the subject images 68 and 69 are respectively detected by a plurality of focus detections as described with reference to FIG. It corresponds to pixels 810a and 810b, 820a and 820b, 830a and 830b, and 840a and 840b. A plurality of focus detection pixels 810a and 810b, 820a and 820b, 830a and 830b, and 840a and 840b respectively corresponding to the subject image areas 680 and 690 in the photometric sensor 16 determined in FIG. Is identified by referring to a correspondence table stored in advance in the control device 18 or the storage device 19. A plurality of focus detection pixel projection images 810, 820, 830 and 840 corresponding to the identified plurality of focus detection pixels 810a and 810b, 820a and 820b, 830a and 830b, and 840a and 840b, respectively, are shown in FIG. .

  FIG. 7D shows a plurality of focus detection pixel projection images 820, 830 and 840 corresponding to the subject image region 680 by hatching. In order to make the drawing easy to see, in FIG. 7D, a plurality of focus detection pixel projection images 810, 820, 830 and 840 corresponding to the subject image region 690 are shown without hatching, and regions other than the subject image region 680 are shown. Assume that the subject image area 690 occupies. As shown in FIG. 7D, the focus detection visual field 81 in the vertical direction is hatched corresponding to only the subject image region 680, the hatched region 811 corresponding to the subject image region 690, and the subject image region 690. No region 812 is included. The vertical focus detection visual field 82 includes a subject image region 680, a hatched region 821 corresponding to the subject image region 690, and an unhatched region 822 corresponding to only the subject image region 690. The horizontal focus detection visual field 83 includes a hatched region 831 corresponding to the subject image region 680 and an unhatched region 832 corresponding to the subject image region 690. The horizontal focus detection visual field 84 includes a hatched area 841 corresponding to the subject image area 680 and an unhatched area 842 corresponding to the subject image area 690.

  As described with reference to FIG. 3A, there are four pairs of focus detection signal sequences respectively corresponding to the focus detection visual fields 81, 82, 83, and 84. In step S103 of FIG. Are obtained. In the example shown in FIG. 7D, when the defocus amount calculation process is performed in the divided region 210 in step S108 of FIG. 4, for example, a pair of vertical direction corresponding to the vertical focus detection field of view 81 is obtained. The focus detection signal sequence is divided by the control device 18 into a pair of partial signal sequences corresponding to the hatched region 811 and a pair of partial signal sequences corresponding to the non-hatched region 812. In that case, based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 811 and the phase difference amount of the pair of partial signal sequences corresponding to the non-hatched region 812, two focus detection data The focus amount is calculated by the control device 18. A hatched region 811 corresponds to both a subject image region 680 including a subject image 68 of a nearby main subject and a subject image region 690 including a subject image 69 of a distant background including trees, and an unhatched region 812 Only a subject image area 690 including a subject image 69 of a distant background including trees is supported. Therefore, the focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 811 is the closest defocus amount, and is controlled as the focus adjustment defocus amount. Determined by device 18.

  In the calculation of the focus detection parameter in step S108 of FIG. 4, for example, when the defocus amount calculation process is performed in the divided region 220, a pair of vertical focus detection signal sequences corresponding to the vertical focus detection field 82 is performed. Are divided by the control device 18 into a pair of partial signal sequences corresponding to the hatched region 821 and a pair of partial signal sequences corresponding to the non-hatched region 822. In that case, based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 821 and the phase difference amount of the pair of partial signal sequences corresponding to the non-hatched region 822, two focus detection data The focus amount is calculated by the control device 18. A hatched area 821 corresponds to both a subject image area 680 including a subject image 68 of a nearby main subject and a subject image area 690 including a far background subject image 69 including a tree, and an unhatched area 822 Only a subject image area 690 including a subject image 69 of a distant background including trees is supported. Therefore, the focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 821 is the closest defocus amount, and is controlled as the focus adjustment defocus amount. Determined by device 18.

  In the calculation of the focus detection parameter in step S108 of FIG. 4, for example, when the defocus amount calculation process is performed in the divided region 230, a pair of vertical focus detection signal sequences corresponding to the horizontal focus detection field 83 is performed. Are divided by the control device 18 into a pair of partial signal sequences corresponding to the hatched region 831 and a pair of partial signal sequences corresponding to the non-hatched region 832. In that case, based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 831 and the phase difference amount of the pair of partial signal sequences corresponding to the non-hatched region 832, two focus detection data The focus amount is calculated by the control device 18. The hatched region 831 corresponds only to the subject image region 680 including the subject image 68 of the nearby main subject, and the non-hatched region 832 corresponds only to the subject image region 690 including the far background subject image 69 including the tree. Correspond. Therefore, the focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 831 is the closest defocus amount, and is controlled as the focus adjustment defocus amount. Determined by device 18.

  In the calculation of the focus detection parameter in step S108 of FIG. 4, for example, when the defocus amount calculation process is performed in the divided region 240, a pair of vertical focus detection signal sequences corresponding to the horizontal focus detection field of view 84 is shown. Are divided by the control device 18 into a pair of partial signal sequences corresponding to the hatched region 841 and a pair of partial signal sequences corresponding to the non-hatched region 842. In that case, based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 841 and the phase difference amount of the pair of partial signal sequences corresponding to the non-hatched region 842, two focus detection data The focus amount is calculated by the control device 18. The hatched area 841 corresponds only to the subject image area 680 including the subject image 68 of the nearby main subject, and the non-hatched area 842 corresponds only to the subject image area 690 including the distant background subject image 69 including the tree. Correspond. Therefore, the focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 841 is the closest defocus amount, and is controlled as the focus adjustment defocus amount. Determined by device 18.

  The focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the area 811 hatched in the focus detection visual field 81 and the pair corresponding to the area 821 hatched in the focus detection visual field 82. The focus detection defocus amounts calculated based on the phase difference amounts of the partial signal sequences correspond to both the subject image regions 680 and 690. A focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the area 831 hatched in the focus detection field 83 and a pair corresponding to the area 841 hatched in the focus detection field 84. The defocus amounts for focus detection calculated based on the phase difference amounts of the partial signal sequences correspond to only the subject image region 680. Therefore, when focusing on the main subject corresponding to the subject image region 680, the calculation is performed based on the phase difference amount of the pair of partial signal sequences corresponding to the region 831 or 841 hatched in the focus detection visual field 83 or 84. The focus detection defocus amount is preferably determined by the control device 18 as the focus adjustment defocus amount.

  FIG. 8 is a flowchart of the imaging process performed by the control device 18. As described above, the control device 18 is a computer including a CPU and a memory, for example. When the CPU executes the computer program stored in the memory, the process of each step constituting the imaging process shown in FIG. 8 is performed.

  In step S <b> 501, the control device 18 determines whether or not an imaging instruction is given by the user via the operation member 17. In the case of negative determination, the process of step S501 is repeated until an affirmative determination is made. If the determination is affirmative, the control device 18 advances the process to step S502. The operation member 17 is, for example, a shutter release button. When the shutter release button is set to a fully pressed state, an affirmative determination is made in step S501.

  In step S <b> 502, the control device 18 performs photoelectric conversion control of the image sensor 6. As the photoelectric conversion control of the image sensor 6, for example, exposure control of a plurality of image pickup pixels arranged in the image sensor 6, read control of a plurality of image signals, and / or amplification control of a plurality of read image signals are performed. Is called.

  In step S503, the control device 18 acquires a plurality of imaging signals that have been read in step S502 and subjected to amplification control.

  In step S504, the control device 18 generates an image based on the plurality of imaging signals acquired in step S503.

  In step S505, the control device 18 records the image generated in step S504 in the storage device 19. When the process of step S505 is completed, this process ends.

  The focus detection device 50 in the present embodiment includes the control device 18 as described above. The control device 18 detects the focus by the phase difference method for each of the divided areas 210, 220, 230, and 240 in the focus detection area 200 provided on the shooting screen 20 (imaging plane 20 b) of the shooting optical system 1. To calculate a plurality of defocus amounts, and determine a defocus amount for focus adjustment used for focus adjustment from among the plurality of defocus amounts. The photometric sensor 16 includes a focus detection area 200 and a search area 162 corresponding to the imaging screen 20 (imaging plane 20b). The control device 18 forms a plurality of images that are respectively imaged in the search area 162 by the imaging optical system 1. A plurality of subject image areas 680 and 690 corresponding to the subject images 68 and 69 are discriminated in the search area 162. When the plurality of subject image areas 680 and 690 are determined in the search area 162, the control device 18 calculates the plurality of divided areas 210, 220, 230, and 240 corresponding to the plurality of subject image areas 680 and 690, respectively. The defocus amount for focus adjustment is determined from the plurality of defocus amounts. Accordingly, it is possible to focus on either the main subject image 68 or the background subject image 69 including the tree. If the defocus amount calculated for the divided region corresponding to the subject image region 680 of the subject image 68 of the main subject is determined as the defocus amount for focus adjustment, the subject image 68 of the main subject can be focused.

  The control device 18 determines the defocus amount corresponding to the phase difference amount of the pair of focus detection signal sequences corresponding to the subject image region 680 and the defocus amount corresponding to the phase difference amount of the pair of focus detection signal sequences corresponding to the subject image region 690. The focus amount is calculated, and the closest defocus amount among the plurality of defocus amounts is determined as the focus adjustment defocus amount. Therefore, it is possible to focus on the subject image 68 of the main subject.

---- Modified example ---
(1) In the above-described embodiment, as shown in FIG. 5, the present invention is applied to an example in which two subject images are included in the focus detection region 200, but three or more subject images are included in the focus detection region 200. The present invention can be applied even in the case where is included. This will be described with reference to FIG.

  FIG. 9 is a diagram illustrating an example in which three subject images 67, 68, and 69 are included in the focus detection area 200 and a diagram for explaining the focus adjustment defocus amount determination process. In FIG. 9A, one focus detection area 200 in the shooting screen 20 includes three subject images 67, 68 and 69. The shooting screen 20 and the focus detection area 200 include a subject image 68 of a main subject, a background subject image 69 including a tree, and a subject image 67 of another subject different from the main subject. Based on the example shown in FIG. 9A, focus detection processing by the control device 18 will be described with reference to FIGS. 9B and 9C.

  FIG. 9B shows a subject image 68 of the main subject, a subject image 69 of the background including trees, and focus detection on the imaging plane 20b (see FIG. 1) corresponding to the shooting screen 20. An area 200, a subject image 67 of another object, four focus detection fields 81, 82, 83 and 84 corresponding to the focus detection area 200 shown in FIG. 3A, and four focus detection fields 81 and 82. , 83, and 84, a plurality of focus detection pixel projection images 810, 820, 830, and 840 are shown in a superimposed manner. In order to make the drawing easy to see, in FIG. 9B, the clear illustration of the background subject image 69 including the tree is omitted, and the region other than the subject image 68 of the main subject and the subject image 67 of another subject is represented by the tree. It is assumed that the background subject image 69 includes the image. In FIG. 9B, a plurality of focus detection pixel projection images 810, 820, 830, and 840 corresponding to the subject images 67, 68, and 69, respectively, as described with reference to FIG. It corresponds to focus detection pixels 810a and 810b, 820a and 820b, 830a and 830b, and 840a and 840b. A plurality of focus detection pixels 810a and 810b, 820a and 820b, 830a and 830b, and 840a and 840b respectively corresponding to the three subject image areas in the photometric sensor 16 determined in step S105 of FIG. It is specified by referring to a correspondence table stored in advance in the control device 18 or the storage device 19. A plurality of focus detection pixel projection images 810, 820, 830, and 840 corresponding to the identified plurality of focus detection pixels 810a and 810b, 820a and 820b, 830a and 830b, and 840a and 840b, respectively, are shown in FIG. 9C. .

  FIG. 9C shows a plurality of focus detection pixel projection images 820, 830 and 840 corresponding to the subject image area of the subject image 68, and a plurality of focus detections corresponding to the subject image area of the subject image 69. Pixel projection images 810, 830 and 840 are shown hatched in another manner. In order to make the drawing easy to see, a plurality of focus detection pixel projection images 810, 820, 830 and 840 corresponding to the subject image area of the subject image 69 are shown without hatching in FIG. Assume that the subject image region of the subject image 69 occupies a region other than the subject image region of the image region and the subject image 68.

  As shown in FIG. 9C, the focus detection visual field 81 in the vertical direction includes only a hatched area 813 that substantially corresponds to the subject image area of the subject image 67, and corresponds to the subject image area of the subject image 69. There are few unhatched regions 812 to be included. The vertical focus detection visual field 82 includes only a hatched area 821 that substantially corresponds to the subject image area of the subject image 68, and has only a few unhatched areas 822 that correspond to the subject image area of the subject image 69. Not included. Since the hatched regions 813 and 821 correspond to different subject images 67 and 68, respectively, the hatched directions are illustrated differently.

  In the horizontal focus detection visual field 83, a hatched region 831 corresponding to the subject image region of the subject image 68, an unhatched region 832 corresponding to the subject image region of the subject image 69, and a subject image of the subject image 67 are displayed. A hatched area 833 corresponding to the area is included. Since the hatched regions 831 and 833 correspond to different subject images 68 and 67, respectively, the hatched directions are illustrated differently. In the horizontal focus detection field 84, a hatched area 841 corresponding to the subject image area of the subject image 68, an unhatched area 842 corresponding to the subject image area of the subject image 69, and a subject image of the subject image 67. A hatched area 843 corresponding to the area is included. Since the hatched areas 841 and 843 correspond to different subject images 68 and 67, respectively, the hatched directions are shown differently.

  As described with reference to FIG. 3A, there are four pairs of focus detection signal trains corresponding to the focus detection fields 81, 82, 83, and 84, respectively. A detection signal sequence is acquired. In the example shown in FIG. 9C, the divided area 210 (see FIG. 3C) corresponding to the focus detection visual field 81 including the hatched area 813 and the focus detection visual field 83 including the hatched area 833. The control device in each of the divided areas 230 (see FIG. 3 (c)) corresponding to, and the divided areas 240 (see FIG. 3 (c)) corresponding to the focus detection visual field 84 including the hatched area 843. By performing the focus detection by 18, a plurality of focus detection parameters corresponding to the subject image area of the subject image 67 can be calculated. In the example shown in FIG. 9C, the divided area 220 (see FIG. 3C) corresponding to the focus detection visual field 82 including the hatched area 821 and the focus detection visual field 83 including the hatched area 831. And a control unit in each of the divided areas 230 (see FIG. 3C) corresponding to, and the divided areas 240 (see FIG. 3C) corresponding to the focus detection visual field 84 including the hatched area 841. By performing the focus detection by 18, a plurality of focus detection parameters corresponding to the subject image area of the subject image 68 can be calculated. In the example shown in FIG. 9C, the divided region 230 (see FIG. 3C) corresponding to the focus detection visual field 83 including the non-hatched region 832 and the focus including the non-hatched region 842. A plurality of focus detection parameters corresponding to the subject image area 690 are calculated by performing focus detection by the control device 18 in each of the divided areas 240 (see FIG. 3C) corresponding to the detection visual field 84. can do.

  In other words, four focus detection parameters are calculated by performing focus detection in each of the four divided areas 210, 220, 230, and 240, and the focus detection parameters calculated in the divided areas 210 are different from each other. The focus detection parameters calculated in the divided region 220 corresponding to the subject image region including the subject image 67 of the subject corresponding to the subject image region including the subject image 68 of the main subject are calculated in the divided regions 230 and 240. The two focus detection parameters are: a subject image region including a subject image 68 of a main subject, a subject image region including a background subject image 69 including a tree, and a subject image region including a subject image 67 of another subject. It corresponds to any of these.

  In the calculation of the focus detection parameter by the control device 18, for example, the phase difference amount of the pair of vertical focus detection signal sequences corresponding to the vertical focus detection visual field 81 and the vertical focus detection visual field 82 are supported. Two focus detection defocus amounts are calculated based on the phase difference amount of the pair of vertical focus detection signal sequences. Of the two focus detection defocus amounts, the control device 18 determines the closest defocus amount as the focus adjustment defocus amount. When the main subject corresponding to the subject image 68 is located closer to the imaging device 100 than the other subject corresponding to the subject image 67, the focus detection defocus amount calculated in the divided region 220, that is, the vertical direction. The focus detection defocus amount calculated based on the phase difference amount of the pair of vertical focus detection signal sequences corresponding to the direction focus detection field 82 is the closest defocus amount, and the focus adjustment defocus Determined as a quantity.

  In the calculation of the focus detection parameter by the control device 18, for example, the focus detection defocus amount is calculated based on the phase difference amount of the pair of vertical focus detection signal sequences corresponding to the horizontal focus detection visual field 83. Instead of that, the pair of focus detection signal sequences are divided into a pair of partial signal sequences corresponding to the hatched region 831, a pair of partial signal sequences corresponding to the non-hatched region 832, and a hatched region 833. It is good also as dividing | segmenting by the control apparatus 18 into a corresponding pair of partial signal sequence. In that case, the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 831, the phase difference amount of the pair of partial signal sequences corresponding to the non-hatched region 832, and the hatched region 833. Based on the phase difference amounts of the pair of partial signal sequences, three defocus amounts for focus detection are calculated by the control device 18. A hatched region 831 corresponds to a subject image region including the subject image 68 of a nearby main subject, and an unhatched region 832 corresponds to a subject image region including a subject image 69 of a distant background including trees. The region 833 thus formed corresponds to a subject image region including a subject image 67 of another subject located between a distant background and a nearby main subject. Therefore, the focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 831 is the closest defocus amount, and is controlled as the focus adjustment defocus amount. Determined by device 18.

  In the calculation of the focus detection parameter by the control device 18, for example, the focus detection defocus amount is calculated based on the phase difference amount of the pair of vertical focus detection signal sequences corresponding to the horizontal focus detection visual field 84. Instead of that, the pair of focus detection signal sequences are divided into a pair of partial signal sequences corresponding to the hatched region 841, a pair of partial signal sequences corresponding to the non-hatched region 842, and a hatched region 843. It is good also as dividing | segmenting by the control apparatus 18 into a corresponding pair of partial signal sequence. In that case, the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 841, the phase difference amount of the pair of partial signal sequences corresponding to the non-hatched region 842, and the hatched region 843. Based on the phase difference amounts of the pair of partial signal sequences, three defocus amounts for focus detection are calculated by the control device 18. A hatched area 841 corresponds to a subject image area including a subject image 68 of a nearby main subject, and an unhatched area 842 corresponds to a subject image area including a subject image 69 of a distant background including trees. An area 843 corresponding to a subject image area includes a subject image 67 of another subject located between a distant background and a nearby main subject. Therefore, the focus detection defocus amount calculated based on the phase difference amount of the pair of partial signal sequences corresponding to the hatched region 841 is the closest defocus amount, and is controlled as the focus adjustment defocus amount. Determined by device 18.

(2) In the embodiment described above, as shown in FIG. 3F, the subject recognition area 161 includes, for example, 4 pixels in the horizontal direction × 4 pixels in the vertical direction, that is, a total of 16 photometric pixels 160. It was. However, the subject recognition area 161 may include the photometric pixels 160 having a larger number of pixels by further reducing the pitch between the photometric pixels 160. When the number of photometric pixels 160 included in the subject recognition area 161 increases, a plurality of subject image areas are discriminated when three or more subject images are included in the focus detection area 200 as shown in FIG. 9A. It becomes easy to do. Therefore, N when the control device 18 divides the pair of focus detection signal sequences into N pairs of partial signal sequences is proportional to the number of photometric pixels 160 included in the subject recognition region 161 corresponding to the focus detection region 200. It may be a value.

(3) In the above-described embodiment, in steps S108 and S109 of FIG. 4, the control device 18 performs a plurality of calculations based on a plurality of phase difference amounts corresponding to each of a plurality of pairs of focus detection signal sequences. Of the defocus amounts, the closest defocus amount is determined as the defocus amount for focus adjustment. However, the control device 18 determines one defocus amount calculated based on the closest phase difference amount among the plurality of phase difference amounts corresponding to each of the plurality of pairs of focus detection signal sequences, as the focus adjustment defocus amount. The focus amount may be determined.

(4) In the above-described embodiment, in step S110 of FIG. 4, the control device 18 performs shooting based on whether or not the focus adjustment defocus amount determined in step S109 or S115 is substantially zero. It is determined whether or not the optical system 1 is at the in-focus position. However, whether or not the photographing optical system 1 is at the in-focus position is determined based on whether or not the lens driving amount of the photographing optical system 1 calculated in step S111 is almost zero by performing step S111 first. It may be determined.

(5) In the embodiment described above, in steps S111 and S112 of FIG. 4, the control device 18 performs focus adjustment control by driving the lens of the photographing optical system 1 based on the defocus amount for focus adjustment. However, the control device 18 may perform focus adjustment control by driving the image sensor 6 based on the defocus amount for focus adjustment.

(6) When the absolute distance information of the subject can be detected based on the distance encoder included in the photographing optical system 1, the control device determines whether or not to execute the focus detection process of FIG. 4 based on the absolute distance information. 18 may be determined in advance. For example, if the distance from the imaging device 100 to the subject is greater than a predetermined distance, the subject image of the subject is sufficiently smaller than the background subject image, and therefore the control device 18 in the search region in step S106 in FIG. It is also possible to determine that the plurality of subject images are not included in the image and to advance the focus detection process to step S115.

(7) The present invention includes not only the focus detection device 50 using the re-imaging optical system 9 shown in FIG. 1 but also the focus detection device 50 having a focus detection sensor using a microlens array, and a microlens array. The focus detection sensor used can also be applied to the focus detection device 50 included in the image sensor.

  You may combine embodiment and the modification which were mentioned above. The present invention is not limited to the above-described embodiments and modifications as long as the characteristics of the present invention are not impaired, and other forms conceivable within the scope of the technical idea of the present invention are also within the scope of the present invention. included.

1 Shooting optical system, 2 half mirror, 3 viewfinder screen,
4 penta prism, 5 eyepiece, 6 image sensor, 7 sub mirror,
8 focus detection sensor, 9 re-imaging optical system, 10 optical axis,
13 focus adjustment device, 14 lens driving motor,
15 Photometric lens, 16 Photometric sensor, 20 Shooting screen,
17 operation member, 18 control device, 19 storage device, 50 focus detection device

Claims (7)

A plurality of focus detection parameters are calculated by performing focus detection by a phase difference method for each of the plurality of divided regions in the focus detection region provided on the imaging plane of the optical system, and the plurality of focus detection parameters. A focus detection means for determining a focus adjustment parameter used for focus adjustment;
A plurality of subject image regions corresponding to each of a plurality of subject images that include the focus detection region and a predetermined region corresponding to the imaging plane and are respectively imaged in the predetermined region by the optical system. A subject image area discriminating means for discriminating with
When the plurality of subject image regions are determined within the predetermined region by the subject image region determination unit, the focus detection unit is operated for the plurality of divided regions respectively corresponding to the plurality of subject image regions. A focus detection apparatus that determines the focus adjustment parameter from among a plurality of focus detection parameters. The focus detection apparatus according to claim 1,
Further comprising a specifying means for the user to specify the focus detection area;
The focus detection apparatus characterized in that when the user designates the focus detection area via the designation means, the subject image area discrimination means discriminates the plurality of subject image areas within the predetermined area. The focus detection apparatus according to claim 1 or 2,
An absolute distance acquisition unit configured to acquire an absolute distance between the plurality of subjects corresponding to the plurality of subject images and the optical system based on information on the optical system;
When the subject image area determination unit detects that one of the plurality of subjects is within a predetermined distance from the optical system based on the absolute distance acquired by the absolute distance acquisition unit. A focus detection apparatus that discriminates the plurality of subject image areas within the predetermined area. The focus detection apparatus according to any one of claims 1 to 3,
The focus detection unit calculates a plurality of defocus amounts as the plurality of focus detection parameters, and determines a closest defocus amount among the plurality of defocus amounts as the focus adjustment parameter. A focus detection apparatus. In the focus detection apparatus according to any one of claims 1 to 4,
The subject image area determining unit calculates a plurality of hue values and a plurality of luminance values respectively representing a hue and a luminance of a plurality of photometric signals generated by a plurality of pixels for photometry in the predetermined area, and the plurality of photometry Determining the plurality of subject image areas within the predetermined area according to whether or not the difference between the plurality of hue values and the difference between the plurality of luminance values among pixels for use is greater than a predetermined threshold value. Feature focus detection device. In the focus detection apparatus according to any one of claims 1 to 5,
The plurality of divided regions are predetermined in a plurality of directions in the focus detection region,
A pair of focal points obtained by photoelectrically converting a pair of light beams that have passed through a pair of pupil regions of the optical system when the focus detection is performed for each of the plurality of divided regions by the focus detection means. A focus detection apparatus characterized in that each of the plurality of focus detection parameters is calculated by the focus detection means based on a phase difference amount of a detection signal string. The focus detection device according to any one of claims 1 to 6,
The optical system;
An image sensor that receives a light beam that has passed through the optical system and outputs an image signal;
Focus adjusting means for performing focus adjustment based on the focus detection performed by the focus detecting means;
Image generating means for generating an image based on the imaging signal output by the imaging element when the optical system is focused on the light receiving surface of the imaging element by the focus adjusting means. An imaging device.

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