JP2011085661A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To drive a photographing optical system to a new focusing position without missing a shutter chance, even in the case where a distance to a subject is changed following a composition changing operation, when the photographing optical system is fixed to the focusing position. <P>SOLUTION: The digital camera includes: a first imaging element; a focus detection means for outputting a signal showing a focus adjustment state of the photographing optical system; a focus adjusting means for driving the photographing optical system to the focusing position, when photographing preparation is instructed; a locking means for locking the driven photographing optical system on the focusing position; a main subject detection means for detecting the position of an image of a main subject on a photographed image; a determination means for determining occurrence of a position change of the main subject after the photographing optical system is locked, when photographing preparation is instructed; and a control means wherein, when the position of the main subject is changed, the photographing optical system is driven to the new focusing position based on a signal output newly from the focus detection means by controlling the focus adjusting means, and then the image of the subject is imaged by controlling a first imaging element. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a digital camera.

  Conventionally, an imaging apparatus that detects a focus adjustment state based on either an output of a focus detection pixel incorporated in an imaging device for photographing or an output of a focus detection sensor provided at a position different from the imaging device Is known (for example, Patent Document 1).

JP 2007-233303 A

  However, in the conventional imaging apparatus, when the distance from the subject changes due to the composition change operation when the driving of the photographing optical system is fixed at the in-focus position, the focus adjustment state is detected again. There is a problem that a photo opportunity is missed.

A digital camera according to a first aspect of the present invention includes a first image sensor that captures an image of a subject through a photographing optical system and outputs an image signal, and a focus that outputs a signal indicating a focus adjustment state of the photographing optical system. When the detection means and the preparation for photographing are instructed, the focus adjusting means for driving the photographing optical system to the in-focus position based on the signal output from the focus detecting means, and the in-focus position is driven by the focus adjusting means. Locking means for locking the photographic optical system to the in-focus position, main subject detecting means for detecting the position occupied by the image of the main subject on the photographed image, and when the start of photographing is instructed, the photographing optical system is A determination unit that determines whether or not there is a change in the position of the main subject after being locked, and if it is determined that there is a change in the position of the main subject, the focus adjustment unit is controlled and newly output by the focus detection unit Trust And a control unit that drives the imaging optical system to a new in-focus position and controls the first image sensor after the imaging optical system is driven to the new in-focus position to capture an image of the subject. It is characterized by providing.
A digital camera according to an eighth aspect of the present invention is provided at a position optically conjugate with the first image pickup device that picks up an image of a subject through a photographing optical system and outputs an image signal. The first focus detection element that detects the focus adjustment state of the photographing optical system and outputs a focus detection signal before the start of photographing, and the focus adjustment state of the photographing optical system are detected by detecting the focus adjustment state of the photographing optical system. A second focus detection element that outputs a detection signal; a first focus adjustment unit that drives the imaging optical system to a first focus position based on the focus detection signal output from the first focus detection element; Based on a focus detection signal output from the bifocal detection element, a second focus adjustment unit that drives the photographing optical system to the second focus position, and a first focus adjustment unit that is driven to the first focus position. Lock to lock the photographic optical system to the first in-focus position Means for detecting movement of the subject after the photographing optical system is locked by the lock means, and photographing for allowing light from the subject to enter the first image sensor and the second focus detector. Operation start means, and when the movement of the locked subject is detected by the subject movement detection means, the second focus adjustment means is based on the second focus detection signal from the second focus detection element. Is driven to the second in-focus position.

According to the present invention, when the main subject has a position change after the photographing optical system is locked at the in-focus position, a new in-focus position is set based on the signal newly output by the focus detection means. An image of the subject can be taken after the photographing optical system is driven.
Further, according to the present invention, the movement of the subject is detected by the subject movement detection means after the photographing optical system is locked at the first focus position based on the first focus detection signal from the first focus detection element. In this case, the imaging optical system can be driven to the second in-focus position based on the second focus detection signal from the second focus detection element.

1 is a configuration diagram of a main part of a digital camera according to an embodiment of the present invention. FIG. 1 is a block diagram illustrating a configuration of a control system of a digital camera according to an embodiment Flowchart for explaining operation of digital camera according to embodiment A flowchart for explaining the operation of the digital camera according to the first and second embodiments. The flowchart explaining operation | movement of the digital camera by 1st Embodiment. The flowchart explaining operation | movement of the digital camera by 1st Embodiment. The flowchart explaining operation | movement of the digital camera by 2nd Embodiment. The flowchart explaining operation | movement of the digital camera by 2nd Embodiment. The flowchart explaining operation | movement of the digital camera by 3rd Embodiment. The flowchart explaining operation | movement of the digital camera by 3rd Embodiment. The flowchart explaining operation | movement of the digital camera by 3rd Embodiment.

-First embodiment-
A camera according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a main configuration of the digital camera 1. An interchangeable lens 2 including a photographing lens L1 and a diaphragm 20 is detachably mounted on the body of the digital camera 1. On the body side of the digital camera 1, a quick return mirror 10, a focusing screen 11, a pentaprism 12, an eyepiece lens 13, an image sensor 14, a first focus detection sensor 15, a second focus detection sensor 16, a photometric sensor 17, and A shutter 21 is provided. The imaging element 14 has imaging pixels arranged two-dimensionally, and incorporates focus detection pixels constituting the second focus detection sensor 16 at a portion corresponding to the focus detection position.

  FIG. 2 is a block diagram of a control system of the digital camera 1 to which the interchangeable lens 2 is attached. In FIG. 2, the components shown in FIG. As shown in FIG. 2, the interchangeable lens 2 includes a photographic lens L <b> 1, a lens control circuit 20, and a lens driving unit 22. The photographing lens L1 includes a plurality of optical lens groups such as an imaging lens and a focus adjustment lens. In FIG. 2, the photographing lens L1 is represented by a single lens. The lens control circuit 20 controls the driving of the focus adjustment lens in the optical axis direction by outputting a drive control signal to a lens driving unit 22 described later. Further, the lens control circuit 20 transmits / receives various information to / from the digital camera 1 via signal contacts (not shown). The lens driving unit 22 is configured by, for example, a stepping motor or the like, and drives a focus adjustment lens that constitutes the photographing lens L1 based on a drive control signal from the lens control circuit 20. The digital camera 1 includes an image sensor 14, a first focus detection sensor 15, a second focus detection sensor 16, a photometric sensor 17, a control circuit 18, an LCD drive circuit 19, a liquid crystal display 191, an operation unit 30, and an auxiliary light emitting unit 33. And a memory card interface 31.

  Referring to FIG. 1, subject light that has entered the digital camera 1 after passing through the photographing lens L1 is guided upward by a quick return mirror 10 positioned as shown by a solid line in FIG. 1 before the shutter release. An image is formed on the focusing screen 11. The subject image formed on the focusing screen 11 is guided to the eyepiece lens 13 and the photometric sensor 17 by the pentaprism 12. As a result, the subject image is observed by the photographer. Part of the subject light passes through the semi-transmissive region of the quick return mirror 10, is reflected downward by the sub mirror 10 a, and enters the first focus detection sensor 15. After the release, the quick return mirror 10 is rotated to the position indicated by the broken line in FIG. 1, and the subject light is guided to the image sensor 14 and the second focus detection sensor 16 via the shutter 21, and the subject image is formed on the imaging surface. Forms an image.

The control system will be described in detail with reference to FIG.
The imaging element 14 is a photoelectric conversion element such as a CMOS having a plurality of imaging pixels arranged two-dimensionally. The image sensor 14 is driven in accordance with the control of the control circuit 18 to be described later, images a subject image input through the imaging lens L1, and outputs an image signal obtained by the imaging. R (red), G (green), and B (blue) color filters are provided on the imaging surface of the imaging device 14 so as to correspond to the pixel positions, respectively. The image signal output from the image sensor 14 is subjected to analog processing (such as gain control) by an AFE circuit (not shown) or the like, and is output to a control circuit 18 described later.

  The first focus detection sensor 15 is provided corresponding to a plurality of focus detection positions set in the shooting screen of the shooting lens L1. The first focus detection sensor 15 includes a pair of CCD line sensors, for example, and outputs a focus detection signal corresponding to the pair of optical images to the control circuit 8. The second focus detection sensor 16 is provided corresponding to a plurality of focus detection positions set in the imaging screen by the imaging lens L1, and as described above, the imaging element 14 in which imaging pixels are two-dimensionally arranged. It is built in and arranged. The second focus detection sensor 16 includes, for example, a pair of focus detection pixels, and outputs a focus detection signal corresponding to the pair of optical images to the control circuit 18 for each focus detection position. Each focus detection pixel of the second focus detection sensor 16 is also provided with a color filter of a predetermined color (for example, G).

  The photometric sensor 17 includes a plurality of pixels (photoelectric conversion elements) arranged two-dimensionally, and outputs a field image signal to the control circuit 18. R (red), G (green), and B (blue) color filters are provided on the imaging surface of the photometric sensor 17 so as to correspond to the pixel positions, and the photometric sensor 17 displays the object field image for each pixel. RGB signals can be output. The scene image signal is used for exposure calculation, main subject detection processing, and composition change determination processing performed by the control circuit 18 as will be described later. The control circuit 18 may perform the exposure calculation, the main subject detection process, and the composition change determination process based on the image signal output from the image sensor 14.

  The control circuit 18 includes a CPU, a ROM, a RAM, and the like (not shown), and is an arithmetic circuit that controls each component of the digital camera 1 and executes various data processing based on a control program. The control program is stored in a nonvolatile memory (not shown) in the control circuit 18. The control circuit 18 calculates the brightness of the subject based on the object scene image signal input from the photometric sensor 17 and calculates the shooting conditions (aperture value, shutter speed, etc.).

  The control circuit 18 functionally includes an image processing unit 18a, an image recording unit 18b, a focus adjustment unit 18c, a lens drive control unit 18d, a main subject detection unit 18e, and a composition change determination unit 18f. The image processing unit 18a performs various image processing such as gamma correction and white balance adjustment on the input image signal to generate image data. Further, the image processing unit 18a generates display image data to be displayed on a liquid crystal display 191 to be described later, based on the image data recorded on the memory card 32.

  The image recording unit 18b compresses the image data generated by the image processing unit 18a by a predetermined method such as JPEG, and records the compressed data in the memory card 32 in a format such as EXIF. The focus adjustment unit 18c determines the focus adjustment state of the photographing lens L1, based on the focus detection signal corresponding to the pair of optical images output from the first focus detection sensor 15 or the second focus detection sensor 16, here the defocus amount. To detect. Then, the focus adjustment unit 18c detects the focus position of the focus adjustment lens included in the photographic lens L1 based on the detected defocus amount. The focus adjusting unit 18c is a first focus detection sensor 15 or a second focus detection sensor 16 corresponding to a focus detection position located in the vicinity of the main subject detected by the main subject detection unit 18e described later on the shooting screen. The focus position may be detected (tracking AF) based on the focus detection signal.

  The lens drive control unit 18d calculates the drive amount of the focus adjustment lens using the focus position detected by the focus adjustment unit 18c. Then, the lens drive control unit 18d outputs a drive instruction signal for the focus adjustment lens to the lens control circuit 20 based on the calculated drive amount, and controls the drive of the focus adjustment lens to the in-focus position. As will be described later, when the focus lock for fixing the focus adjustment lens at the in-focus position is set, the lens drive control unit 18d does not output a drive instruction signal. That is, at the time of focus lock, the lens drive control unit 18d prevents the focus adjustment lens that has already been driven to the in-focus position from being driven while being fixed (locked).

  The main subject detection unit 18e performs main subject detection processing on the shooting screen based on a known technique using the object scene image signal input from the photometry sensor 17. The main subject detection unit 18e creates, for example, a template combined image (for example, a rectangular region) having a predetermined region in the captured image based on the input object scene image signal, and uses this template image as a reference for detecting the main subject. Used as The template image is image data corresponding to a human face extracted by, for example, a known face detection process based on the object scene image signal. The main subject detection unit 18e calculates the difference between the object scene image signal sequentially input after the template image is created and the template image in accordance with the imaging by the photometric sensor 17. Then, the main subject detection unit 18e detects, on the object scene image, a position where the main subject occupies a region having a small difference from the template image (main subject position).

  The composition change determination unit 18f determines whether or not the composition of the captured image has been changed by a user operation based on the main subject position detected by the main subject detection unit 18e. In this case, the composition change determination unit 18f receives the object scene image signal acquired when the focus adjustment lens is locked at the in-focus position (when the focus is locked) and a shooting instruction by the user, as will be described later. It is determined whether or not the composition has been changed by the user's operation using the object scene image signal acquired later. That is, the composition change determination unit 18f determines whether or not the position occupied by the main subject on the captured image when the focus is locked and the position occupied by the main subject on the captured image when the shooting instruction is issued are changed. The focus adjustment unit 18c, the lens drive control unit 18d, the main subject detection unit 18e, and the composition change determination unit 18f will be described in detail later.

  The memory card interface 31 is an interface to which the memory card 32 can be attached and detached. The memory card interface 31 writes image data to the memory card 32 or reads image data recorded on the memory card 32 based on the control of the control circuit 18. The memory card 32 is a semiconductor memory card such as a compact flash (registered trademark) or an SD card.

  The LCD drive circuit 19 is a circuit that drives the liquid crystal display 191 based on a command from the control circuit 18. The liquid crystal display 191 displays the display data created by the control circuit 18 based on the image data recorded on the memory card 32 in the reproduction mode. The liquid crystal display 191 is configured to display a so-called live view image. The live view is a display form in which the quick return mirror 10 is flipped upward before the release and an image captured by the image sensor 14 is displayed on the liquid crystal display 191 in real time.

  The operation unit 30 is various switches that accept user operations, and outputs various operation signals corresponding to the operation contents to the control circuit 18. The operation unit 30 includes a power switch, a release switch, other setting menu display changeover switches, a setting menu determination button, a focus lock button, and the like. The focus lock button is operated when the user performs shooting with changing the composition of the shot image, for example, and when the focus adjustment lens driven to the focus position according to the shooting preparation instruction is fixed at the focus position. To be operated.

  The operation unit 30 can set an AF-S mode, a still image shooting mode or a moving image shooting mode as a shooting mode, and a live view mode for displaying the above live view image. The AF-S mode is a mode in which the focus adjustment lens drive is fixed (locked) at the in-focus position detected in the initial processing by the focus adjustment unit 18c during the shooting preparation operation. For example, the user can change the composition of the shot image. It is set when shooting with accompanying. In the following description, the case where the focus lock button is operated or the case where the focus adjustment lens is locked at the focus position while the AF-S mode is selected is referred to as focus lock.

  The auxiliary light emitting unit 33 includes a light source that emits infrared light, for example, and lights up in response to a light emission (lighting) instruction from the control circuit 18 when the focus adjustment unit 18c detects the focus adjustment state. In this case, based on the object scene image signal input from the photometric sensor 17, the control circuit 18 outputs the above-described signal for instructing light emission when the luminance of the main subject is lower than a predetermined luminance value.

  Hereinafter, the operation of the digital camera 1 when a shooting preparation instruction is issued in response to a half-press operation of the release switch by the user will be described. In the digital camera 1 according to the first embodiment, the focus adjustment lens is driven to the in-focus position during the shooting preparation operation, and the shooting instruction according to the full pressing operation of the release switch by the user even in the focus lock state. If the composition change is determined at this time, a new in-focus position is detected. When the difference between the in-focus position where the focus adjustment lens is locked and the new in-focus position detected after the shooting instruction is greater than or equal to a predetermined value, the digital camera 1 determines the newly detected in-focus position. Drive the focus adjustment lens to the position. Further, the digital camera 1 performs focus adjustment (hereinafter referred to as normal phase difference AF) based on the focus detection signal output from the first focus detection sensor 15 during the shooting preparation operation, and newly focuses after the shooting instruction. When the position is detected, focus adjustment (hereinafter referred to as image plane phase difference AF) is performed based on the focus detection signal output from the second focus detection sensor 16. This will be described in detail below.

(1) During shooting preparation When a half-press operation signal is input from the operation unit 30 in response to a half-press operation of the release switch by the user, the focus adjustment unit 18 c is based on the focus detection signal output from the first focus detection sensor 15. As described above, the defocus amount is calculated, and the in-focus position is detected. When the in-focus position is detected, the lens drive control unit 18d outputs a drive instruction signal to the lens control unit 20 to drive the focus adjustment lens to the in-focus position. When the focus lock button is operated by the user and an operation signal is input from the operation unit 30, the lens drive control unit 18d outputs a signal to stop driving when the operation signal is input to the lens control circuit 20. Then, the focus adjustment lens is stopped and locked.

  When the focus adjustment lens is driven to the focus position detected by the first normal phase difference AF when the AF-S mode is set, the lens drive control unit 18d focuses the drive of the focus adjustment lens. A fixing instruction signal for stopping and locking at the position is output to the lens control circuit 20. As a result, the focus adjustment lens is locked at the in-focus position until a full-press operation signal is input from the operation unit 30 in response to the full-press operation of the release switch by the user. Note that the position where the focus adjustment lens is driven is detected by an encoder (not shown) or the like and output to the control circuit 18.

  When the focus adjustment lens is focus-locked, the main subject detection unit 18e performs main subject detection processing based on the object scene image signal input from the photometric sensor 17. Note that, as described above, the main subject detection unit 18e occupies the main subject on the shooting screen in an area where the difference from the template image serving as a reference for main subject detection is the smallest in the scene image signal. Detect as position. At this time, the area including the main subject has the same size as the area defined by the template image. Therefore, the main subject detection unit 18e stores the coordinate value of the center of the rectangular area surrounding the area having the smallest difference from the template image as a main subject position in a memory (not shown).

(2) At the time of shooting instruction When the focus adjustment lens is focus-locked according to the half-press operation signal and the main subject is detected, a full-press operation signal is output from the operation unit 30 according to the user's full-press operation of the release switch. The case where it is input will be described. At this time, the main subject detection unit 18e performs a main subject detection process using the newly input object scene image signal in the same manner as described above, and performs a new main subject position (ie, coordinates of the center of the rectangular area). Value) in memory.

  The composition change determination unit 18f compares the main subject position detected when the focus adjustment lens is focus-locked with the main subject position newly detected after the release switch is fully pressed, The presence or absence of composition change is determined. In this case, the composition change determination unit 18f calculates the difference between the main subject position detected when the focus is locked and the main subject position newly detected after the shooting instruction. That is, the composition change determination unit 18f calculates a difference value stored in the memory between the coordinate value of the center of the rectangular area when the focus is locked and the coordinate value of the center of the rectangular area after the full-press operation signal is input. Then, the composition change determination unit 18f determines that the composition change operation has been performed by the user when the calculated difference value is equal to or greater than a predetermined value. Hereinafter, the case where it is determined that the composition change operation has not been performed and the case where it has been determined that the composition change operation has been performed will be described separately. When the control circuit 18 inputs a full-press operation signal from the operation unit 30 while driving the focus adjustment lens to the in-focus position detected by the tracking AF described above, a composition change operation described below is performed. The same processing is performed.

-When no composition change operation is performed-
When it is determined that the composition change operation has not been performed, the control circuit 18 controls each unit to perform the photographing process while the focus adjustment lens is in the focus lock state. In this case, the control circuit 18 drives the quick return mirror 10 to a position indicated by a broken line in FIG. 1 via an actuator (not shown) (mirror up). When the mirror is raised, the control circuit 18 opens the shutter 21 for a period corresponding to the shutter time calculated based on the object scene image signal from the photometric sensor 17 to expose the image sensor 14.

  When the shutter time has elapsed and the shutter 21 is closed and the subject light to the image sensor 14 is blocked, the control circuit 18 causes the image sensor 14 to output an image signal. The image processing unit 18a performs the above-described various image processing on the input image signal to generate image data. Then, the image recording unit 18b performs compression processing on the image data generated by the image processing unit 18a by a predetermined method such as JPEG, and records it in the memory card 32 in a format such as EXIF. When the image data is recorded on the memory card 32, the control circuit 18 drives the quick return mirror 10 to the position indicated by the solid line in FIG. 1 via an actuator (not shown) (mirror down).

-When a composition change operation is performed-
When it is determined that the composition change operation has been performed, the image plane phase difference AF is performed to newly detect the focus adjustment state of the photographing lens L1, that is, the focus position of the focus adjustment lens. In this case, when a full-press operation signal is input from the operation unit 30, the control circuit 18 mirrors the quick return mirror 10 through an actuator (not shown) and opens the shutter 21. That is, the control circuit 18 allows subject light to enter the image sensor 14 and the second focus detection sensor 16. As a result, the image sensor 14 and the second focus detection sensor 16 are exposed.

  At this time, the control circuit 18 drives the image sensor 14 by a rolling shutter system (electronic shutter system) to output an image signal. The rolling shutter system is an imaging system in which the image sensor 14 sequentially outputs an image signal for each scanning line (pixel row). The control circuit 18 temporarily stores the image signal output from the image sensor 14 in a memory (not shown). Furthermore, the focus adjustment unit 18c calculates a defocus amount based on the focus detection signal output from the second focus detection sensor 16, and detects the focus position of the focus adjustment lens.

  The control circuit 18 determines that the focus position newly detected by the image plane phase difference AF based on the focus detection signal output from the second focus detection sensor 16 is the focus position where the focus adjustment lens is focus-locked, that is, normal It is determined whether or not the focus position detected by the phase difference AF has changed. In this case, the control circuit 18 determines whether or not the difference between the in-focus position newly detected by the image plane phase difference AF and the in-focus position detected by the normal phase difference AF is greater than or equal to a predetermined value. . When the difference between the two in-focus positions is equal to or greater than a predetermined value, the control circuit 18 determines that the in-focus position has changed. Note that the predetermined value is a value set so that an image with a shifted focus adjustment state is not captured even when a composition change operation is performed by the user, and is determined by an experiment or the like. . This predetermined value is stored in advance in a memory (not shown).

  When the in-focus position has changed (when the difference between the two in-focus positions is greater than or equal to a predetermined value), the lens drive control unit 18d outputs a drive signal to the lens control circuit 20 and the image plane phase difference. The focus adjustment lens is driven to the in-focus position newly detected by AF. When the focus adjustment lens is driven to a new in-focus position, the control circuit 18 drives the image sensor 14 by a rolling shutter method (electronic shutter method) to output an image signal. The image processing unit 18a performs the above-described various image processing on the input image signal to generate image data. The generated image data is recorded on the memory card 32 in a format such as EXIF after being subjected to compression processing or the like by the image recording unit 18b as in the case where the composition change operation is not performed. The control circuit 18 deletes the image signal acquired after the mirror is raised and the shutter 21 is opened and temporarily stored in the memory.

  When the in-focus position has not changed (when the difference between the two in-focus positions is less than the predetermined value), the lens drive control unit 18d continues the focus-locked state of the focus adjustment lens. That is, the lens drive control unit 18d prohibits the focus adjustment lens from being driven to the in-focus position newly detected by the image plane phase difference AF. Then, the image processing unit 18a reads the image signal acquired after the mirror up and the shutter 21 is opened and temporarily stored in the memory, and performs the above-described various image processing on the image signal to obtain the image data. Generate. The generated image data is recorded on the memory card 32 in a format such as EXIF after being subjected to compression processing or the like by the image recording unit 18b as in the case where the composition change operation is not performed.

  The operation of the digital camera 1 according to the embodiment will be described with reference to the flowcharts shown in FIGS. A program for performing the processes of FIGS. 3 to 6 is stored in a memory (not shown) in the control circuit 18, and when the user turns on the power switch and inputs an operation signal for instructing power on by the operation unit 30, the control circuit 18 is started and executed.

  In step S101 of FIG. 3, initialization is performed, and in step S102, power-on processing is performed on each unit in the digital camera 1, and the process proceeds to step S103. In step S103, it is determined whether or not the power switch is turned off. When an operation signal for instructing to turn off the power is input from the operation unit 30 according to the operation of the power switch, an affirmative determination is made in step S103 and the process proceeds to step S104. In step S104, a power-off process is performed and the process ends. If an operation signal for instructing power off is not input from the operation unit 30, a negative determination is made in step S103 and the process proceeds to step S105.

  In step S105, it is determined whether or not the user has pressed the release switch halfway. If a half-press operation signal is input from the operation unit 30 in response to a half-press operation of the release switch, an affirmative determination is made in step S105 and the process proceeds to step S106. If no half-press operation signal is input from the operation unit 30, a negative determination is made in step S105, and the process returns to step S103.

  In step S106, a shooting preparation process is performed, and the process proceeds to step S107. The photographing preparation process will be described later with reference to FIG. In step S107, it is determined whether or not the user continues to press the release switch halfway. If a half-press operation signal is input from the operation unit 30, an affirmative determination is made in step S107 and the process proceeds to step S108. If the half-press operation signal is not input, a negative determination is made in step S107 and the process returns to step S103.

  In step S108, it is determined whether the AF-S mode is set and the focus adjustment lens is not driven to the in-focus position. When the AF-S mode is set and the focus adjustment lens is not driven to the in-focus position, an affirmative determination is made in step S108 and the process returns to step S107. If a negative determination is made in step S108, the process proceeds to step S109.

  In step S109, it is determined whether or not the user has pressed the release switch fully. If a full-press operation signal is input from the operation unit 30, an affirmative determination is made in step S109 and the process proceeds to step S110. If the full-press operation signal is not input, a negative determination is made in step S109 and the process returns to step S103. In step S110, a photographing process is performed, and the process returns to step S103. The photographing process will be described later with reference to the flowchart of FIG.

  Next, imaging preparation processing will be described with reference to the flowchart of FIG. In step S201, it is determined whether the focus is locked. If the focus is not locked, a negative determination is made in step S201 and the process proceeds to step S202. If the focus is locked, an affirmative decision is made in step S201 and the process proceeds to step S208 described later. In step S202, the defocus amount is calculated by the normal phase difference AF, and the process proceeds to step S203.

  In step S203, it is determined whether or not the focus position of the focus adjustment lens is detected by the normal phase difference AF in step S202. If the in-focus position is detected, an affirmative determination is made in step S203 and the process proceeds to step S204. If the in-focus position is not detected, a negative determination is made in step S203, and the process proceeds to step S209 described later. In step S204, the focus adjustment lens is driven to the in-focus position via the lens control circuit 20, and the process proceeds to step S205.

  In step S205, it is determined whether or not driving of the focus adjustment lens is completed. When the focus adjustment lens is driven to the in-focus position, an affirmative determination is made in step S205 and the process proceeds to step S206. If the focus adjustment lens is being driven, a negative determination is made in step S205 and the determination process is repeated. In step S206, it is determined whether the AF-S mode is set or the focus lock button is operated. If the AF-S mode is set, or if an operation signal is input from the operation unit 30 in response to the operation of the focus lock button, an affirmative determination is made in step S206 and the process proceeds to step S207. In step S207, the focus adjustment lens is locked at the in-focus position, and the process proceeds to step S208. If the AF-S mode is not set and the focus lock button has not been operated, a negative determination is made in step S206 and the process proceeds to step S208. In step S208, the position of the main subject is detected using the object scene image signal input from the photometric sensor 17, and the shooting preparation process is terminated.

  If a negative determination is made in step S203, the process proceeds to step S209, and the focus adjustment lens is driven to a predetermined position (for example, a position where the focal length becomes ∞) via the lens control circuit 20, and the process proceeds to step S210. In step S210, as in step S205, it is determined whether or not the driving of the focus adjustment lens has ended. If a positive determination is made in step S210, the process proceeds to step S211. If a negative determination is made, the determination process is repeated. In step S211, it is determined whether or not the AF-S mode is set. If the AF-S mode is not set, a negative determination is made in step S211 and the process proceeds to step S208. If the AF-S mode is set, an affirmative determination is made in step S211 and the process proceeds to step S212. In step S212, the focus adjustment lens is locked at a predetermined position, and the photographing preparation process ends.

  Next, the photographing process will be described with reference to FIG. In step S301, the position of the main subject is detected using the object scene image signal input from the photometric sensor 17, and the process proceeds to step S302. In step S302, it is determined whether or not a composition change operation has been performed by the user, or whether or not the release switch has been fully pressed during tracking AF. If the difference between the main subject position detected in step S208 in FIG. 4 and the main subject position detected in step S301 is greater than or equal to a predetermined value, an affirmative determination is made in step S302 and the process proceeds to step S310 described later. If the difference in the main subject position is less than the predetermined value, a negative determination is made in step S302 and the process proceeds to step S303. When tracking AF is being performed, it is determined whether or not the release switch has been fully pressed while the focus adjustment lens is being driven. When a full-press operation signal is input from the operation unit 30 while the focus adjustment lens is being driven, an affirmative determination is made in step S302 and the process proceeds to step S310 described later. If a push operation signal is input, a negative determination is made in step S302 and the process proceeds to step S303. Details of the image plane phase difference AF process in step S310 will be described later with reference to FIG.

  In step S303, the quick return mirror 10 is raised, and the process proceeds to step S304. In step S304, the shutter 21 is opened, and in step S305, the image sensor 14 is exposed. In step S306 when the time corresponding to the shutter speed has elapsed from step S304, the shutter 21 is closed and the process proceeds to step S307. In step S307, an imaging process is performed. That is, the image signal output from the image sensor 14 is subjected to various image processing to generate image data, compressed to a predetermined compression rate (for example, JPEG), and then an image file is generated and recorded in the memory card 32. To do. In step S307, if the composition has not been changed, image data is generated based on the image signal output in step S305. When the composition is changed, image data is generated based on the image signal output in the image plane phase difference AF process (FIG. 6, step S402 or S409) described later. In step S308, the quick return mirror 10 is mirrored down and the photographing process is terminated.

  The image plane phase difference AF process will be described with reference to the flowchart shown in FIG. In step S401, the quick return mirror 10 is raised, and the shutter 21 is opened, and the process proceeds to step S402. In step S402, the image sensor 14 and the second focus detection sensor 16 are exposed by the electronic shutter method, and the process proceeds to step S403. At this time, the image signal output from the image sensor 14 is temporarily stored in a memory (not shown). In step S403, the defocus amount is calculated by the image plane phase difference AF, and the process proceeds to step S404.

  In step S404, it is determined whether or not the focus position of the focus adjustment lens is newly detected by the image plane phase difference AF in step S403. If a new in-focus position is detected, an affirmative determination is made in step S404 and the process proceeds to step S405. If a new in-focus position is not detected, a negative determination is made in step S404 and the process proceeds to step S410 described later. In step S405, a change between the in-focus position detected by the normal phase difference AF in step S202 of FIG. 4 and the in-focus position newly detected by the image plane phase difference AF in step S403 is detected, that is, two in-focus positions are detected. The position difference is calculated and the process proceeds to step S406.

  In step S406, it is determined whether or not there is a change in the in-focus position detected by the two focus detection processes. If there is a change in the focus position, that is, if the difference value of the focus position calculated in step S405 is greater than or equal to a predetermined value, an affirmative determination is made in step S406 and the process proceeds to step S407. If there is no change in the in-focus position, that is, if the difference value of the in-focus position calculated in step S405 is less than a predetermined value, a negative determination is made in step S406 and the process proceeds to step S410 described later.

  In step S407, the focus adjustment lens is driven to the in-focus position newly detected by the image plane phase difference AF, and the process proceeds to step S408. In step S408, it is determined whether or not the driving of the focus adjustment lens is finished. When the focus adjustment lens is driven to the in-focus position newly detected in step S403, an affirmative determination is made in step S408 and the process proceeds to step S409. If the focus adjustment lens is being driven to the newly detected focus position, a negative determination is made in step S408 and the determination process is repeated.

  In step S409, the image sensor 14 is exposed by the electronic shutter method to output an image signal, temporarily stored in a memory (not shown), and the process proceeds to step S410. In this case, the image signal output in step S402 and stored in the memory is deleted. In step S410, the shutter 21 is closed and the image plane phase difference AF process is terminated.

According to the digital camera 1 of the first embodiment described above, the following operational effects can be obtained.
(1) The image pickup device 14 picks up an image of a subject through the taking lens L1 and outputs an image signal. The first focus detection sensor 15 is provided at a position optically conjugate with the image pickup device 14, and takes a picture. Before starting, the focus adjustment state of the photographic lens L1 is detected and a focus detection signal is output. The second focus detection sensor 16 is incorporated in the image sensor 14, detects the focus adjustment state of the photographic lens L1, and outputs a focus detection signal. The lens drive control unit 18d drives the photographic lens L1 to the in-focus position based on the focus detection signal output from the first focus detection sensor 15, and sets the photographic lens L1 driven to the in-focus position to the in-focus position. Fix (lock). The main subject detection unit 18e and the composition change determination unit 18f detect the movement of the subject after the photographing lens L1 is locked, and when the start of photographing is instructed based on the operation signal from the operation unit 30, the control circuit 18 Allows light from the subject to enter the image sensor 14 and the second focus detection sensor 16.

  When the start of shooting is instructed, if the movement of the locked subject is detected by the composition change determination unit 18f, the lens drive control unit 18d is based on the focus detection signal output from the second focus detection sensor 16. The photographic lens L2 is driven to the in-focus position. In other words, the lens drive controller 18d drives the photographing lens L1 to the in-focus position based on the focus detection signal from the first focus detection sensor 15 until the photographing lens L1 is locked, and the photographing lens L1 is locked. After that, the taking lens L1 is driven to a new in-focus position based on the focus detection signal from the second focus detection sensor 16. Therefore, even when the distance to the subject changes due to the composition change operation by the user, the user's operation for redoing the detection of the focus adjustment state becomes unnecessary, and it is possible to prevent the shutter chance from being missed. Further, after the composition change operation is performed, the image sensor 14 and the second focus detection sensor 16 are exposed by the rolling shutter method, and therefore, a time lag due to the opening / closing operation of the shutter 21 for exposing the second focus detection sensor 16. Can be prevented.

(2) When the difference between the new focus position based on the focus detection signal from the second focus detection sensor 16 and the focus position when the photographing lens L1 is locked is greater than or equal to a predetermined value, the control circuit 18 The lens driving control unit 18d is controlled to drive the photographing lens L1 to a new in-focus position based on the focus detection signal from the second focus detection sensor 16. In other words, if the difference between the new focus position based on the focus detection signal from the second focus detection sensor 16 and the focus position when the photographic lens L1 is locked is less than a predetermined value, the photographic lens L1. Was not driven to a new in-focus position. Therefore, even after the user's composition change operation is performed, if the distance from the subject has not changed significantly, the photographing lens L1 is not driven, so that unnecessary power consumption can be suppressed. it can. Furthermore, when a composition change operation is performed and there is no significant change in the distance to the subject, the image sensor 14 is exposed by the rolling shutter method and outputs an image signal (FIG. 6, step S402). It is possible to prevent a time lag from the shooting start instruction to the image signal output.

(3) The main subject detection unit 18e detects the position of the main subject on the shooting screen using the photometric object scene image signal output from the photometry sensor 17. Therefore, the presence / absence of a composition change operation by the user can be determined.

-Second Embodiment-
A second embodiment according to the present invention will be described with reference to the drawings. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first embodiment. In this embodiment, when the subject brightness is low, that is, when AF auxiliary light irradiation is required, if the composition of the shooting screen is changed by the user, the normal phase difference is maintained even when the focus is locked. This is different from the first embodiment in that an in-focus position is newly detected by AF. The electronic camera 1 according to the second embodiment may not include the second focus detection sensor 16 in the first embodiment.

  The control circuit 18 starts photometry when a half-press operation signal is input from the operation unit 30 in response to a half-press operation of the release switch by the user. That is, the control circuit 18 causes the photometric sensor 17 to perform imaging, and calculates brightness information of the object scene, that is, a luminance value, from the signal value of the object scene image signal output after charge accumulation. Then, the control circuit 18 outputs a signal for instructing the auxiliary light emitting unit 33 to emit light when the calculated luminance of the subject is a low luminance lower than a predetermined value.

  In the following description, since the processing until the release switch is fully pressed by the user is the same as that of the digital camera 1 according to the first embodiment, the processing after the release switch is fully pressed will be described. . In other words, when the subject has low brightness, the focus adjustment lens is focus-locked, and the main subject is detected. In response to the user's full-press operation (shooting instruction) on the release switch, the full-press operation signal is output from the operation unit 30. A case where is input will be described. At this time, the main subject detection unit 18e performs main subject detection processing in the same manner as in the first embodiment, using the newly input scene image signal, and stores the new main subject position in the memory. Store.

  As in the case of the first embodiment, the composition change determination unit 18f newly inputs the main subject position detected when the focus adjustment lens is focus-locked and the full-press operation signal from the operation unit 30. The difference between the detected position and the main subject position is calculated, and it is determined whether or not the difference value is a predetermined value or more. Then, the composition change determination unit 18f determines that the composition change operation has been performed by the user when the difference value is equal to or greater than a predetermined value.

-When a composition change operation is performed-
When the composition change operation is performed, the control circuit 18 newly detects the in-focus position of the focus adjustment lens by the normal phase difference AF. In this case, the focus adjustment unit 18c determines the focus position of the focus adjustment lens using the focus detection signal output from the first focus detection sensor 15 corresponding to the focus detection position located in the vicinity of the latest main subject position. Newly detect.

  The control circuit 18 determines whether or not the focus position newly detected by the normal phase difference AF after the composition change operation is changed from the focus position where the focus adjustment lens is focus-locked. In this case, the control circuit 18 determines whether or not the difference between the newly detected in-focus position and the in-focus position where the focus adjustment lens is focus-locked is greater than or equal to a predetermined value. When the difference between the two in-focus positions is equal to or greater than a predetermined value, the control circuit 18 determines that the in-focus position has changed.

  When the focus position changes, the lens drive control unit 18d outputs a drive signal to the lens control circuit 20 to drive the focus adjustment lens to the newly detected focus position. When the in-focus position has not changed, the lens drive control unit 18d continues the state in which the focus adjustment lens is focus-locked. That is, the lens drive control unit 18d prohibits driving the focus adjustment lens to the newly detected in-focus position. Then, the control circuit 18 controls each part in the digital camera 1 to perform photographing processing. Note that the shooting process of the digital camera 1 in the second embodiment performs the same process as the shooting process when the composition change operation is not performed in the first embodiment.

-When no composition change operation is performed-
When the composition change operation is not performed, the control circuit 18 performs the imaging process without performing the new focus position detection process as described above. That is, the control circuit 18 performs photographing processing with the focus adjustment lens being focus-locked.

  With reference to the flowcharts shown in FIGS. 3, 4, 7 and 8, the operation of the digital camera 1 according to the embodiment will be described. 3, 4, 7, and 8 are stored in a memory (not shown) in the control circuit 18, and an operation to turn on the power from the operation unit 30 when the user turns on the power switch. When a signal is input, it is started and executed by the control circuit 18. 3 and 4 are the same as the processes described in the first embodiment, and therefore the description will be made mainly with reference to the flowcharts shown in FIGS.

  Each process of step S311 (main subject detection) and step S312 (composition change or full-press determination during tracking AF) in FIG. 7 is performed in steps S301 (main subject detection) and step S302 (composition change or tracking in FIG. 5). This is the same as the determination of whether or not the button is fully pressed during AF. However, if the determination in step S312 is negative, step S313 is skipped and the process proceeds to step S314.

  In step S313, normal phase difference AF processing is performed, and the process proceeds to step S314. Details of the processing in step S313 will be described later using the flowchart shown in FIG. Each process from step S314 (mirror up) to step S319 (mirror down) is the same as each process from step S303 (mirror up) to step S308 (mirror down) in FIG.

  Next, details of the normal phase difference AF processing in step S313 will be described with reference to the flowchart shown in FIG. In step S411, the defocus amount is calculated based on the focus detection signal from the first focus detection sensor 15 by the normal phase difference AF, and the process proceeds to step S412. The defocus amount is calculated based on the focus detection signal corresponding to the focus detection position located in the vicinity of the main subject position detected in step S311 in FIG.

  In step S412, it is determined whether or not the focus position of the focus adjustment lens is newly detected by the normal phase difference AF in step S411. When the in-focus position is newly detected, an affirmative determination is made in step S412 and the process proceeds to step S413. If the in-focus position is not detected, a negative determination is made in step S412 and the normal phase difference AF process is terminated. In step S413, a change between the in-focus position detected in step S202 of FIG. 4 and the in-focus position newly detected in step S411 is detected, that is, the difference between the two in-focus positions is calculated, and the process proceeds to step S414. .

  In step S414, it is determined whether or not there is a change in the in-focus position detected by the two focus detection processes. If there is a change in the focus position, that is, if the difference value of the focus position calculated in step S413 is greater than or equal to a predetermined value, an affirmative determination is made in step S414 and the process proceeds to step S415. If there is no change in the focus position, that is, if the difference value of the focus position calculated in step S413 is less than a predetermined value, a negative determination is made in step S414, and the normal phase difference AF process is terminated.

  In step S415, the focus adjustment lens is driven to the focus position newly detected in step S411, and the process proceeds to step S416. In step S416, it is determined whether or not driving of the focus adjustment lens has ended. When the focus adjustment lens is driven to the newly detected in-focus position, an affirmative determination is made in step S416 and the normal phase difference AF process is terminated. If the focus adjustment lens is being driven to the newly detected focus position, a negative determination is made in step S416 and the determination process is repeated.

According to the digital camera 1 according to the second embodiment described above, the following operational effects can be obtained.
(1) The image sensor 14 captures an image of a subject via the photographing lens L1 and outputs an image signal, and the first focus detection sensor 15 outputs a focus detection signal indicating the focus adjustment state of the photographing lens L1. When the preparation for photographing is instructed, the lens drive control unit 18d drives the photographing lens L1 to the in-focus position based on the focus detection signal output from the first focus detection sensor 15, and is driven to the in-focus position. The photographing lens L1 is fixed (locked) at the in-focus position. The main subject detection unit 18e detects the position occupied by the image of the main subject on the photographed image, and the composition change determination unit 18f, when instructed to start photographing, detects the main subject after the photographing lens L1 is locked. The presence or absence of a position change is determined. When the composition change determination unit 18f determines that there is a change in the position of the main subject, the control circuit 18 controls the lens drive control unit 18d and the focus newly output by the first focus detection sensor 15. Based on the detection signal, the taking lens L1 is driven to a new in-focus position. Further, the control circuit 18 controls the image sensor 14 to capture an image of the subject after the photographing lens L1 is driven to a new in-focus position. Therefore, even when the distance to the subject changes due to the composition change operation by the user, the user's operation for redoing the detection of the focus adjustment state becomes unnecessary, and it is possible to prevent missing a photo opportunity.

(2) When the luminance of the subject is low, the lens drive control unit 18d focuses the photographing lens L1 based on the focus detection signal output from only the first focus detection sensor 15 after the preparation for photographing is instructed. Drive to position. Therefore, like the second focus detection sensor 16 provided with a color filter, it is possible to prevent a decrease in focus detection accuracy due to the influence of AF auxiliary light (for example, infrared light) emitted from the auxiliary light emitting unit 33.

-Third embodiment-
With reference to the drawings, a third embodiment of the present invention will be described. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first embodiment. In the present embodiment, for example, when the live view mode is set, that is, in the mirror-up state, the focus position is changed by the image plane phase difference AF when the shooting preparation operation and the shooting operation are performed. It differs from the first embodiment in that detection is performed. Note that the electronic camera 1 according to the third embodiment may not include the first focus detection sensor 15 in the first embodiment.

  When the live view mode is set by operating the operation unit 30, the control circuit 18 raises the quick return mirror 10, opens the shutter 21, and guides the subject light that has passed through the photographing lens L 1 to the image sensor 14. Let them be. Then, the control circuit 18 sequentially reads image signals from the image sensor 14 at a predetermined cycle, for example, at a 1/30 second cycle. Then, each time image signals are sequentially read out, the image processing unit 18a generates image data based on the read image signals and outputs the image data to the LCD drive circuit 19 to display an image corresponding to the image data on the liquid crystal display. Display on the device 191.

(1) During shooting preparation When a half-press operation signal is input from the operation unit 30 in response to a half-press operation of the release switch by the user, the focus adjustment unit 18c outputs from the second focus detection sensor 16 due to the image plane phase difference AF. Based on the focus detection signal thus obtained, the defocus amount is calculated as described above. When the defocus amount is calculated and the focus position is detected, the lens drive control unit 18d outputs a drive instruction signal to the lens control unit 20 to drive the focus adjustment lens to the focus position. The subsequent processing is the same as that of the digital camera 1 in the first embodiment. However, the main subject detection unit 18e detects the position of the main subject on the shooting screen using the image signal output from the image sensor 14. The method of detecting the position of the main subject by the main subject detection unit 18e is the same as that performed using the object scene image signal from the photometric sensor 17 in the first or second embodiment.

(2) At the time of shooting instruction When the focus adjustment lens is focus-locked at the in-focus position and the main subject is detected, a full-press operation signal is input from the operation unit 30 in response to the user's full-press operation of the release switch. The case will be described. The control circuit 18 outputs an image signal from the image sensor 14 and stores it in the memory, and also outputs a focus detection signal from the second focus detection sensor 16. Then, the main subject detection unit 18e performs main subject detection processing using the image signal newly input from the image sensor 14, and stores the new main subject position in the memory.

  The composition change determination unit 18f calculates a difference between the main subject position detected when the focus adjustment lens is focus-locked and the main subject position newly detected after the full-press operation signal is input, and the difference value Is determined to be greater than or equal to a predetermined value. Then, the composition change determination unit 18f determines that the composition change operation of the shooting screen has been performed by the user when the difference value is equal to or greater than the predetermined value. Hereinafter, the case where it is determined that the composition change operation has not been performed and the case where it has been determined that the composition change operation has been performed will be described separately.

-When a composition change operation is performed-
When the composition change operation is performed, the focus adjustment unit 18c newly detects the in-focus position of the focus adjustment lens based on the image plane phase difference AF. Then, the control circuit 18 determines whether or not the focus position newly detected by the image plane phase difference AF has changed from the focus position where the focus adjustment lens is focus-locked. That is, the control circuit 18 determines whether or not the difference between the newly detected in-focus position and the in-focus position where the focus adjustment lens is focus-locked is greater than or equal to a predetermined value. When the difference between the two in-focus positions is equal to or greater than a predetermined value, the control circuit 18 determines that the in-focus position has changed.

  When the focus position changes, the lens drive control unit 18d outputs a drive signal to the lens control circuit 20 to drive the focus adjustment lens to the newly detected focus position. Then, the control circuit 18 drives the image sensor 14 by an electronic shutter method, and outputs an image signal from the image sensor 14. The image processing unit 18a performs the above-described various image processing on the input image signal to generate image data. The generated image data is recorded on the memory card 32 in a format such as EXIF after being subjected to compression processing or the like by the image recording unit 18b as in the case where the composition change operation is not performed. The control circuit 18 deletes the image signal acquired when the full-press operation signal is input and temporarily stored in the memory.

  When the in-focus position has not changed, the lens drive control unit 18d continues the state in which the focus adjustment lens is focus-locked. That is, the lens drive control unit 18d prohibits the focus adjustment lens from being driven to the in-focus position newly detected by the image plane phase difference AF. The image processing unit 18a performs image processing on the image signal that is output from the image sensor 14 and temporarily stored in the memory when the full-press operation signal is input, and generates image data. The image recording unit 18b compresses the image data generated by the image processing unit 18a by a predetermined method such as JPEG, and records the compressed data in the memory card 32 in a format such as EXIF.

-When no composition change operation is performed-
When the composition change operation is not performed, the control circuit 18 does not perform the new focus position detection process based on the image plane phase difference AF as described above. In this case, the image processing unit 18a performs image processing on the image signal that is output from the image sensor 14 and temporarily stored in the memory when the full-press operation signal is input, and generates image data. Then, the image recording unit 18b performs compression processing on the image data generated by the image processing unit 18a by a predetermined method such as JPEG, and records it in the memory card 32 in a format such as EXIF.

  With reference to the flowcharts shown in FIGS. 3, 9, 10 and 11, the operation of the digital camera 1 according to the embodiment will be described. 3, 9, 10, and 11 are stored in a memory (not shown) in the control circuit 18, and an operation for instructing to turn on the power by the operation unit 30 when the power switch is turned on by the user. When a signal is input, it is started and executed by the control circuit 18. Since the processing in FIG. 3 is the same as the processing described in the first embodiment, the description will focus on the flowcharts shown in FIG. 9, FIG. 10, and FIG.

  The shooting preparation process in step S106 of FIG. 3 will be described with reference to FIG. Step S221 (focus lock determination) in FIG. 9 performs the same processing as step S201 (focus lock determination) in FIG. In step S222, the second focus detection sensor 16 is exposed to output a focus detection signal, and the process proceeds to step S223. In step S223, the defocus amount is calculated using the image plane phase difference AF, that is, the focus detection signal output in step S222, and the process proceeds to step S224. Each process from step S224 (focus position detection determination) to step S233 (focus adjustment lens is locked) is performed from step S203 (focus position detection determination) to step S212 (focus adjustment lens is locked) in FIG. It is the same as the processing.

  Next, the photographing process in step S110 of FIG. 3 will be described with reference to FIG. In step S321, the image sensor 14 is exposed by the electronic shutter method, and the process proceeds to step S322. At this time, the image signal output from the image sensor 14 is stored in a memory (not shown). In step S322, the position of the main subject is detected using the image signal acquired in step S321, and the process proceeds to step S323.

  The processing of step S323 (determination of whether or not full pressing is performed during composition change or tracking AF) is the same as the processing of step S302 (determination of whether or not full pressing is performed during composition change or tracking AF) in FIG. In step S324, image plane phase difference AF processing is performed, and the flow proceeds to step S325. Details of the image plane phase difference AF process will be described later with reference to FIG. In step S325, the imaging process is terminated after the imaging process is performed. That is, the image signal output from the image sensor 14 is subjected to various image processing to generate image data, compressed to a predetermined compression rate (for example, JPEG), and then an image file is generated and recorded in the memory card 32. To do. In step S325, if the composition has not been changed, or if the composition has been changed as described later but the focus position has not changed, an image is output based on the image signal output in step S321. Data is generated. Further, in step S325, when the composition is changed and the in-focus position is changed, based on the image signal (FIG. 11, step S427) output from the image sensor 14 by the image plane phase difference AF process described later. Image data is generated.

  Details of step S324 (image plane phase difference AF processing) in FIG. 10 will be described with reference to FIG. In step S421, the defocus amount is calculated based on the focus detection signal from the second focus detection sensor 16 based on the image plane phase difference AF, and the process proceeds to step S422. The defocus amount is calculated based on the focus detection signal corresponding to the focus detection area located in the vicinity of the main subject position detected in step S322 in FIG. Each process from step S422 (focus position detection determination) to step S427 (shooting exposure) is the same as each process from step S404 (focus position detection determination) to step S409 (shooting exposure) in FIG. is there.

According to the digital camera 1 according to the third embodiment described above, the following operational effects can be obtained.
(1) The image sensor 14 captures an image of a subject via the photographing lens L1 and outputs an image signal, and the second focus detection sensor 16 outputs a focus detection signal indicating the focus adjustment state of the photographing lens L1. When the preparation for photographing is instructed, the lens drive control unit 18d drives the photographing lens L1 to the in-focus position based on the focus detection signal output from the second focus detection sensor 16, and is driven to the in-focus position. The photographing lens L1 is fixed (locked) at the in-focus position. The main subject detection unit 18e detects the position occupied by the image of the main subject on the photographed image, and the composition change determination unit 18f, when instructed to start photographing, detects the main subject after the photographing lens L1 is locked. The presence or absence of a position change is determined. When the composition change determination unit 18f determines that there is a change in the position of the main subject, the control circuit 18 controls the lens drive control unit 18d and the focus newly output by the second focus detection sensor 16. Based on the detection signal, the taking lens L1 is driven to a new in-focus position. Further, the control circuit 18 controls the image sensor 14 to capture an image of the subject after the photographing lens L1 is driven to a new in-focus position. Therefore, even when the distance to the subject changes due to the composition change operation by the user, the user's operation for redoing the detection of the focus adjustment state becomes unnecessary, and it is possible to prevent the shutter chance from being missed.

(2) When the live view mode is set, the image generation unit 18a generates display image data that is not recorded on the memory card 32, based on the image signal output from the image sensor 14. When the image generation unit 18a generates the display image data in the live view mode, the lens drive control unit 18d detects the focus detected only from the second focus detection sensor 16 after the preparation for shooting is instructed. The taking lens L1 is driven to the in-focus position based on the signal. Accordingly, since the focus detection signal and the image signal can be output without performing the mirror up and mirror down of the quick return mirror 10 when shifting from the live view mode to the shooting operation, occurrence of a time lag is prevented. be able to.

  In addition, the present invention is not limited to the above-described embodiment 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. The embodiments and modifications used in the description may be configured by appropriately combining them.

14 ... image sensor, 15 ... first focus detection sensor,
16 ... second focus detection sensor, 17 ... photometric sensor,
18... Control circuit, 18 a.
18c: Focus adjustment unit, 18d: Lens drive control unit,
18e: main subject detection unit, 18f: composition change determination unit,
30 ... operation unit

Claims (8)

A first image pickup device that picks up an image of a subject through a photographing optical system and outputs an image signal;
Focus detection means for outputting a signal indicating a focus adjustment state of the photographing optical system;
When imaging preparation is instructed, based on the signal output from the focus detection unit, a focus adjustment unit that drives the imaging optical system to a focus position;
Lock means for locking the photographing optical system driven to the in-focus position by the focus adjusting means in the in-focus position;
Main subject detection means for detecting the position occupied by the image of the main subject on the captured image;
When the start of shooting is instructed, a determination unit that determines whether or not there is a change in position of the main subject after the imaging optical system is locked by the locking unit;
When it is determined that there is a change in the position of the main subject, the focus adjustment unit is controlled, and the imaging optical system is moved to a new in-focus position based on a signal newly output by the focus detection unit. And a control unit configured to control the first imaging element to capture an image of the subject after the imaging optical system is driven to the new in-focus position. The digital camera according to claim 1, wherein
The control means controls the focus adjustment means to control the new focus when the difference between the new focus position and the focus position when locked by the lock means is a predetermined value or more. A digital camera, wherein the photographing optical system is driven to a position. The digital camera according to claim 1 or 2,
The main subject detection means includes a second image sensor that captures an image of the subject and generates image data for photometry, and uses the image data for photometry generated by the second image sensor, A digital camera for detecting a position of the main subject. The digital camera according to any one of claims 1 to 3,
The focus detection means includes a first focus detection element provided at a position optically conjugate with the first image sensor, and a second focus detection element incorporated in the first image sensor,
The focus adjusting unit drives the imaging optical system to the in-focus position based on a signal from the first focus detection element until the imaging optical system is locked by the locking unit, and the locking unit After the photographing optical system is locked by the above, the photographing optical system is driven to the new in-focus position based on a signal from the second focus detection element. The digital camera according to claim 4, wherein
The focus adjusting unit moves the imaging optical system to the in-focus position based on the signal output only from the first focus detection element after the preparation for imaging is instructed when the luminance of the subject is low. A digital camera characterized by driving. The digital camera according to claim 4 or 5,
Further comprising display image generation means for generating display image data without recording on a storage medium based on the image signal output from the first image sensor;
When generating the display image data by the display image generation means, the focus adjustment means is based on the signal output only from the second focus detection element after the preparation for photographing is instructed. And a digital camera for driving the photographing optical system to a focus position. The digital camera according to any one of claims 1 to 6,
The digital camera characterized in that the locking means includes a manual operation member, and the imaging optical system driven to the in-focus position is locked in the in-focus position in accordance with an operation of the manual operation member. A first image pickup device that picks up an image of a subject through a photographing optical system and outputs an image signal;
A first focus detection element which is provided at a position optically conjugate with the first imaging element, detects a focus adjustment state of the imaging optical system before starting imaging, and outputs a focus detection signal;
A second focus detection element that is incorporated in the first image sensor and detects a focus adjustment state of the photographing optical system and outputs a focus detection signal;
First focus adjustment means for driving the photographing optical system to a first in-focus position based on a focus detection signal output from the first focus detection element;
Based on a focus detection signal output from the second focus detection element, second focus adjustment means for driving the photographing optical system to a second focus position;
Locking means for locking the photographing optical system driven to the first in-focus position by the first focus adjustment means in the first in-focus position;
Subject movement detection means for detecting movement of the subject after the photographing optical system is locked by the locking means;
Photographing operation start means for allowing light from the subject to enter the first imaging element and the second focus detection element;
When the movement of the subject after the lock is detected by the subject movement detection unit, the second focus adjustment unit is configured to perform the photographing optical system based on the second focus detection signal from the second focus detection element. Is driven to the second in-focus position.

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