JP2013003501A - Camera - Google Patents

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JP2013003501A
JP2013003501A JP2011137206A JP2011137206A JP2013003501A JP 2013003501 A JP2013003501 A JP 2013003501A JP 2011137206 A JP2011137206 A JP 2011137206A JP 2011137206 A JP2011137206 A JP 2011137206A JP 2013003501 A JP2013003501 A JP 2013003501A
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means
focus
switching
imaging
af
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JP5961929B2 (en
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Tetsuo In
哲生 因
Hiroaki Takahara
宏明 高原
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Nikon Corp
株式会社ニコン
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Abstract

PROBLEM TO BE SOLVED: To provide a camera operating while switching between an imaging-surface phase difference AF and a contrast AF.SOLUTION: A camera comprises: an imaging device in which pixels for imaging and pixels for focus detection are two-dimensionally arranged on an imaging surface, the pixels for imaging being arrayed over the entire imaging surface and the pixels for focus detection being arrayed on a part of the imaging surface; an imaging optical system; first focusing means which performs focusing by a phase difference detection method on the basis of output signals of the pixels for focus detection; second focusing means which performs focusing by a contrast method on the basis of output signals of the pixels for imaging; image processing means which recognizes a main object; switching prediction means which predicts switching from one to the other of the first and second focusing means on the basis of a positional relationship between the main object and a focus detection area; start-up means which, when the switching is predicted, starts the other focusing means; and switching means which, after the other focusing means is started, switching from the one to the other focusing means.

Description

  The present invention relates to a camera having a plurality of focus adjustment methods.

  The imaging pixels for imaging the subject image are arranged over the entire imaging screen on the imaging element, and the focus detection pixels for the phase difference detection method are regularly arranged, and the focus of the contrast method is used by using the output of the imaging pixels. There is known a camera that performs detection (hereinafter referred to as contrast AF) and performs focus detection by a phase difference detection method (hereinafter referred to as image plane phase difference AF) using an output of a focus detection pixel (hereinafter referred to as image plane phase difference AF). For example, see Patent Document 1).

JP 2009-244429 A

  However, in the conventional camera described above, the focus detection pixels are arranged instead of the imaging pixels even in the vicinity of the imaging screen where the light amount is reduced due to optical restrictions, so that the image information from the imaging pixels is reduced. There's a problem.

  An imaging device in which imaging pixels and focus detection pixels are two-dimensionally arranged on the imaging surface, and the imaging pixels are arranged over the entire imaging surface, and focus detection is set to a part of the imaging surface. An imaging element in which focus detection pixels are arranged in a region, a photographing optical system that forms a subject image on the imaging surface of the imaging element, and a focus of the photographing optical system by a phase difference detection method based on an output signal of the focus detection pixel A first focus adjusting means for adjusting; a second focus adjusting means for adjusting the focus of the photographing optical system by a contrast method based on an output signal of the imaging pixel; and a main subject by processing an image picked up by the image pickup device From one of the first focus adjustment means and the second focus adjustment means based on the positional relationship between the main subject recognized by the image processing means and the focus detection area. other A switching prediction means for predicting switching to the focus adjustment means, an activation means for activating the other focus adjustment means that is the switching destination when switching is predicted by the switching prediction means, and the other of the switching destinations by the activation means Switching means for switching from one focus adjusting means to the other focus adjusting means after activation of the other focus adjusting means.

  According to the present invention, it is possible to switch between the image plane phase difference AF and the contrast AF while restricting the decrease in the image information to the center of the photographing screen that can be easily corrected.

The figure which shows the structure of the hybrid AF camera of one embodiment The figure which shows an example of the focus detection area set to the imaging | photography screen The figure which shows the example of an arrangement | sequence of the pixel for imaging and the pixel for focus detection in the focus detection area | region of the long side direction of an imaging | photography screen The figure which shows the example of an arrangement | sequence of the pixel for an imaging and the pixel for a focus detection in the focus detection area | region of the short side direction of an imaging | photography screen A flowchart showing an AF control program according to an embodiment FIG. 5 is a flowchart illustrating an AF control program according to an embodiment, FIG. 6 is a diagram for explaining switching between image plane phase difference AF and contrast AF based on the positional relationship between a human face area and a focus detection area.

  FIG. 1 is a block diagram illustrating a configuration of a hybrid AF camera (hereinafter simply referred to as a camera) according to an embodiment. In FIG. 1, illustration and description of camera devices and circuits not directly related to the hybrid AF function are omitted. In FIG. 1, a camera 1 includes a photographic lens 2, an image sensor 3, an AFE (Analog Front End) circuit 4, an image processing circuit 5, a contrast AF circuit 6, a phase difference AF circuit 7, a lens driving circuit 8, a memory 9, and a monitor 10. , A memory card 11, an interface 12, an operation member 13, a battery 14, a controller 15, and the like.

  Although the photographing lens 2 is illustrated as a single lens, it is composed of a plurality of lens groups including a zooming lens and a focusing lens, and forms a subject image on the imaging surface of the image sensor 3. The imaging device 3 is composed of a CMOS image sensor or the like in which a plurality of pixels are two-dimensionally arranged on a light receiving surface, and photoelectrically converts a subject image formed by the photographing lens 2 and outputs an analog image signal.

  FIG. 2 is a diagram showing a photographing screen 3a of the camera 1. A plurality of imaging pixels and focus detection pixels are two-dimensionally arranged on the imaging surface of the imaging device 3 corresponding to the imaging screen 3a, and each of these pixels includes a microlens and a light receiving unit. In this embodiment, line-shaped focus detection areas a to k are set along the long side direction of the photographing screen 3a at 11 positions in the center of the photographing screen 3a.

  The imaging pixels are arranged in a Bayer pattern over the entire area of the imaging screen 3a, receive light passing through the exit pupil of the imaging lens 2 (see FIG. 1), and output an image signal corresponding to the subject image. On the other hand, as shown by the hatched portion in FIG. 3A, the focus detection pixel is formed in a line shape along the long side direction of the shooting screen 3a at the center of the shooting screen 3a corresponding to each of the focus detection areas a to k. And receiving a light passing through a partial region of the photographic lens 2 and outputting a focus detection signal indicating a focus adjustment state of the photographic lens 2.

  FIG. 3B is a partially enlarged view showing the arrangement of the light receiving areas of the imaging pixels R, G, B and the focus detection pixels S1, S2 in the horizontal (long side direction of the photographing screen 3a) area of the focus detection area. FIG. In FIG. 3B, each “mass” surrounded by vertical and horizontal lines indicates an imaging pixel region. A square indicated by a solid line in each square indicates a mask opening, and indicates a light receiving area of each pixel through which the light reaches the light receiving part. In FIG. 3B, a region surrounded by a semicircle indicates a mask opening portion of the focus detection pixel, and indicates a light receiving region of each pixel through which the light reaches the light receiving portion. R, G, and B represent an imaging red pixel, an imaging green pixel, and an imaging blue pixel, respectively. In FIG. 3, illustration of the microlens and the light receiving unit of each pixel is omitted.

  In this embodiment, the shape of the light receiving regions (mask openings) of the imaging pixels R, G, and B is a regular square. However, the shape of the light receiving regions of the imaging pixels R, G, and B is a regular square. For example, it may be circular.

  In this embodiment, an example in which the shape of the light receiving region (mask opening) of the focus detection pixels S1 to S4 is a semicircular shape is shown. Further, in the pair of focus detection pixels S1 and S2 in the horizontal direction shown in FIG. 3B, the light receiving area is arranged to be deviated left and right with respect to the pixel center.

  Note that the shape of the light receiving region of the focus detection pixel is not limited to a semicircular shape, and may be, for example, a rectangle in which the R, G, and B light receiving regions (mask opening portions) of the imaging pixel are approximately bisected vertically or horizontally.

  An imaging device in which imaging pixels and focus detection pixels are two-dimensionally arranged on the imaging surface is already known, and detailed illustration and description of these pixels will be omitted.

  In the horizontal region of the focus detection region, a pair of focus detection pixels S1 and S2 receive a light beam that has passed through the pair of regions of the exit pupil of the photographing lens 2, and the horizontal direction of the photographing lens 2 (the length of the photographing screen 3a). A focus detection signal indicating the focus adjustment state in the side direction is output.

  Note that the focus detection area of the shooting screen 3a is not limited to the arrangement of this embodiment as long as it is set at the center of the shooting screen 3a. Further, the number and shape of the focus detection regions are not limited to the number and shape of this embodiment. Furthermore, the arrangement of the focus detection pixels arranged corresponding to each focus detection area is not limited to the arrangement of this embodiment.

  Returning to FIG. 1, the AFE circuit 4 performs analog processing such as correlated double sampling and gain adjustment on the analog image signal, and converts the analog-processed image signal into digital image data. The image processing circuit 5 performs various types of image processing (color interpolation processing, gradation conversion processing, contour enhancement processing, white balance adjustment processing, image compression processing, image expansion processing, etc.) on the digital image data.

  The contrast AF circuit 6 is a circuit that detects a focusing lens position where the contrast of image signals output from the imaging pixels R, G, and B reaches a peak. The phase difference AF circuit 7 calculates a defocus amount indicating the focus adjustment state of the focusing lens based on the focus detection signals output from the pair of focus detection pixels (S1, S2).

  The lens driving circuit 8 drives the focusing lens of the photographing lens 2 to adjust the focus, and also drives the zooming lens to change the focal length. The memory 9 is a storage element such as a ROM or a RAM that stores various programs and various information. The monitor 10 is an LCD that displays a through image captured by the image sensor 3, a captured image, and various types of information. The interface 12 writes images and various information data to the memory card 11 and reads images and various information data from the memory card 51.

  The operation member 13 includes various switches such as a release half-press and full-press switch, a zoom switch, a mode switch, a menu switch, a cross switch, and an OK switch. The battery 14 supplies power to the devices and circuits of the camera 1. The controller 17 is composed of a CPU and its peripheral components, and controls various operations of the camera 1 such as imaging, exposure, focus adjustment (AF), image display and the like, and executes an AF program described later to execute contrast AF and image plane position. The phase difference AF is switched and controlled.

<Operation in portrait shooting mode>
5 and 6 are flowcharts illustrating the hybrid AF control according to the embodiment. The controller 15 of the camera 1 starts executing the hybrid AF control program shown in FIGS. 5 and 6 when the power switch of the operation member 13 of the camera 1 is turned on and the photographing mode is set by the mode selector.

  In step 1, it is confirmed whether or not the portrait photographing mode is selected by the mode selector of the operation member 13. In portrait shooting mode, set the main subject in the center of the shooting screen and shoot as it is, or set the main subject in the center of the shooting screen and focus the shooting lens 2 on the main subject, then change the composition In many cases, the main subject is set again in the periphery of the shooting screen, and shooting is performed for both buildings and landscapes.

  In the former case, the focus of the photographic lens 2 is adjusted by the defocus amount detected in any of the focus detection areas a to k set at the center of the photographic screen 3a shown in FIG. The photographing lens 2 is focused on the main subject by AF to perform photographing.

  On the other hand, in the latter case, once the main subject is set at the center of the shooting screen, the shooting lens 2 is focused on the main subject by the image plane phase difference AF, and then the main subject is changed along with the change of the angle of view of the photographer. Deviates from the focus detection areas a to k at the center of the shooting screen. In this case, since the image plane phase difference AF for the main subject cannot be performed, the AF control for the main subject is continued by switching to the contrast AF.

Here, in the portrait shooting mode according to the present embodiment, as a method for the camera to recognize the main subject, there are a method in accordance with a user's manual setting operation and a method in which the camera automatically recognizes. First, an example of a method determined by manual operation will be described. The user selects an arbitrary AF area from a plurality of AF areas by a manual selection operation, and determines the selected AF area as an AF area to be used in AF. When a focusing operation is performed on a subject existing in the determined AF area, the camera recognizes the subject as a main subject. On the other hand, an example of how the camera automatically recognizes the main subject will be described. The camera detects a “face” existing in the field of view (through image) using a known face recognition technique. The camera recognizes the detected “face” as the main subject.
In the following description, the description will be continued assuming that the camera adopts a method of automatically recognizing a main subject.

  If the portrait photographing mode is not set in step S1, the process proceeds to step S2, and the subject existing in the AF area designated in advance for phase difference AF (or corresponding to the closest subject) is set as the main subject. After setting, image plane phase difference AF control is executed by the phase difference AF circuit 7 (see FIG. 1) to focus the photographing lens 2 on the main subject. Thereafter, the process proceeds to step S4 by pressing the release button of the operation member 13 in step S3. In step S <b> 4, an image is picked up by the image pickup device 3, image processing is performed, and an image is recorded on the memory card 11.

  On the other hand, if the portrait shooting mode is set in step S1, the process proceeds to step S5, where the phase difference AF circuit 7 applies the main subject captured in any of the focus detection areas a to k in the center of the shooting screen. Image plane phase difference AF control is performed. In step S6 after focusing by the image plane phase difference AF control, the image is processed by the image processing circuit 5 to detect a human face, and the positional relationship between the face range and the focus detection areas a to k is confirmed. When a face of a person is detected by the face recognition process, a face recognition frame indicating the range of the person's face is displayed superimposed on the through image displayed on the monitor 10 in step S7.

  Here, FIG. 7 shows an example in which the face recognition frame 21 is superimposed and displayed on the face of the person displayed on the monitor 10. In FIG. 7, the reference numerals of the focus detection areas a to k shown in FIG. 2 are omitted. In FIG. 7A, the person's face is captured almost at the center of the shooting screen, and the person's face is detected in the areas a, b, f, and g in the focus detection areas a to k shown in FIG. ing. In FIG. 7B, the person's face is captured on the left side of the shooting screen, and the person's face is detected in the leftmost area d of the focus detection areas a to k. In FIG. 7B, the main subject (person's face) is detected not only in the focus detection area d, but also in image-required pixels arranged on the left side of the focus detection area d in the figure. That is, in the state of FIG. 7B, the AF calculation by the phase difference AF circuit 7 using the output of the focus detection area d is possible, and the output of the pixel for the image capturing the main subject (face) is used. The AF calculation by the contrast AF circuit 6 is also possible.

  7A and 7B, in a focus detection area where a human face is detected in the focus detection areas a to k, a line mark (AF area mark) indicating the area of the monitor 10 is used. Any one of a to k) is turned on and is actively displayed.

  On the other hand, in FIG. 7C, the human face is captured at the left end of the shooting screen, and no human face is detected in any of the focus detection areas a to k. That is, the human face is out of the focus detection areas a to k of the image plane phase difference AF, and in this state, the image plane phase difference AF cannot be performed. That is, in FIG. 7C, only the AF calculation by the contrast AF circuit 6 using the output of the pixel for the image capturing the main subject (face) is possible.

  Returning to FIG. 5, it is determined in step S8 whether or not the release button of the operation member 13 has been pressed. If released, the process proceeds to step 4. In step 4, imaging is performed by the imaging device 3, image processing is performed, and an image is recorded on the memory card 11. On the other hand, if not released, the process proceeds to step S9.

  In step S9, it is predicted whether or not the face area of the person is out of the focus detection areas a to k of the image plane phase difference AF. For example, as shown in FIG. 7A, a human face is captured at the center of the screen and focused by image plane phase difference AF, and then the camera orientation (posture) adjustment operation (composition change operation) by the user. Therefore, as shown in FIG. 7B, it is assumed that the person's face is arranged on the left side of the shooting screen and the composition is set such that Mt. At this time, if the user's camera orientation (posture) adjustment operation (composition change operation) goes too far, the face of the person moves to the left end of the shooting screen, resulting in the state shown in FIG. In this case, as described above, the human face deviates from the focus detection areas a to k, and the image plane phase difference AF cannot be performed.

  In this way, the face (main subject) of the person initially detected in a plurality of focus detection areas among the 11 focus detection areas a to k at the center of the shooting screen is the focus detection area at the top, bottom, left, and right ends, for example, When detected in any one of the areas d, e, or a to c, or the areas i to k (in other words, the main subject is the focus detection area for the image plane phase difference AF). The camera predicts that the face area of the person will deviate from the focus detection areas a to k of the image plane phase difference AF in the near future (when it exists near the boundary with the focus detection area for contrast AF).

When it is predicted that the face area of the person is out of the focus detection areas a to k of the image plane phase difference AF (in the case of FIG. 7B, the process proceeds to step S10). The contrast AF circuit 6 starts calculation by the contrast AF circuit 6 using the input image signal (output of image pixels included in the face frame). In the present embodiment, until the time before step S10 (that is, until step S9), the contrast AF circuit 6 is supplied with power but the AF calculation operation is stopped. In order to save energy, the power supply to the contrast AF circuit 6 itself may be cut off until step S9, and the AF calculation may be started by turning on the power to the contrast AF circuit 6 from step S10. However, while the face area of the person is detected in any of the focus detection areas a to k (in other words, the main subject exists in an area where execution of the image plane phase difference AF is prioritized. ), The image plane phase difference AF is executed based on the focus detection result of the focus detection area of the image plane phase difference AF in which the main subject (face) is detected, and the contrast AF is not executed (in other words, in this scene, the contrast is The contrast calculation (AF calculation) is performed by the AF circuit 6, but the focusing operation (AF lens drive control) using the AF calculation result is not performed).
That is, when the main subject (face) approaches the vicinity of the boundary between the detection area of the image plane phase difference AF and the detection area of the contrast AF, the calculation operation by the contrast AF circuit that has not been performed is started. Thus, in the vicinity of the boundary between the detection areas of both AF methods, the operations of both AF circuits (the contrast AF circuit 6 and the phase difference AF circuit 7) are overlapped. Thereby, the output value from the contrast AF circuit 7 in a state where the focus on the main subject is obtained by the image plane phase difference AF (that is, the output value of the contrast AF circuit 7 when the main subject is in focus) ) Can be obtained.

  In step S11, the face area of the person is not detected in any of the focus detection areas a to k of the image plane phase difference AF, and the person face area is out of the focus detection areas a to k of the image plane phase difference AF. Confirm whether or not. When the face area of the person is detected in any of the focus detection areas a to k, the process returns to step S9 and the above process is repeated.

  On the other hand, if it is determined in step S11 that the main subject has deviated from the focus detection areas a to k of the image plane phase difference AF (a person's face area is predicted to deviate from the focus detection areas a to k of the image plane phase difference AF). After that, as shown in FIG. 7C, when the face area of the person actually deviates from the focus detection areas a to k), the process proceeds to step S12, and the contrast already activated (in step S10). Based on the output from the AF circuit 6, contrast AF is executed and image plane phase difference AF is stopped. That is, in this step S12, the AF operation for the main subject is completely shifted (switched) from the image plane phase difference AF to the contrast AF.

  When shifting from the image plane phase difference AF to the contrast AF, the calculation operation by the contrast AF circuit 6 has already been started as already described in step S10. During the transition period (a period in which the phase difference AF circuit 7 and the contrast AF circuit 6 are calculating in parallel), the main subject is AF-tracked and focused based on the output of the phase difference AF circuit 7. continuing. For this reason, when shifting from the image plane phase difference AF to contrast AF, the output of the contrast AF circuit 6 during startup (during AF calculation) may be taken over as it is to shift to contrast AF. Then, as the contrast AF operation after the transition, a normal (well-known) contrast AF operation is performed.

  In the present embodiment, the power supply to the phase difference AF circuit 7 is continued during the period in which this contrast AF (focusing operation on the main subject based on the output of the contrast AF circuit 6) is performed. The arithmetic operation in the circuit 7 is not performed. In this step 12, the power supply itself to the phase difference AF circuit 7 may be stopped for energy saving.

  In step S13 after shifting to contrast AF, it is determined whether or not the release button of the operation member 13 has been pressed. If released, the process proceeds to step S14. In step S <b> 14, an image is picked up by the image pickup device 3, image processing is performed, and an image is recorded on the memory card 11. On the other hand, if not released, the process proceeds to step S15 in FIG.

  In step S15, it is confirmed whether or not the main subject (person's face area) is within the focus detection areas a to k of the image plane phase difference AF. That is, here, in the case opposite to that described in step S9, that is, the main subject moves from the focus detection area for contrast AF into any one of the focus detection areas a to k for image plane phase difference AF. In other words, it is determined whether or not it is necessary to enter a preparatory operation (operation described later in step S16) for shifting from contrast AF to image plane phase difference AF. If the face area of the person is detected in at least one of the focus detection areas a to k, the process proceeds to step S16. In step S16, the phase difference AF circuit 7 is started, that is, the calculation operation by the phase difference AF circuit 7 is started (if the power supply to the phase difference AF circuit 7 was stopped before step S16, the power supply was started. Start the calculation operation above). At this time, the focus detection calculation is executed using the focus detection signal of the focus detection area in which the human face is detected by the phase difference AF circuit 7, but the focusing lens is not driven using the calculation result.

  In step S15, when the main subject is present in any of the focus detection areas a to k, the calculation operation (AF calculation) by the phase difference AF circuit 7 is started. However, the calculation by the phase difference AF circuit 7 may be started at a slightly earlier timing. For example, whether or not the main subject exists in a region just before the main subject reaches the focus detection regions a to k (a pixel region one pixel before or a predetermined number of pixels before the focus detection regions a to k). If a main subject exists in the area in front of the detected object, the calculation by the phase difference AF circuit 7 may be started.

In step 17, it is determined whether or not to switch from contrast AF to image plane phase difference AF. In the present embodiment, if the main subject is completely present in the focus detection areas a to k of the image plane phase difference AF (in the state of FIG. 7A), it has already been activated (in step S16). Based on the output from the phase difference AF circuit 7, the phase difference AF is executed and the contrast AF is stopped. That is, in this step S17, the AF operation for the main subject is completely shifted (switched) from the contrast AF to the image plane phase difference AF.
It should be noted that this AF operation is switched at a slightly earlier stage (front area), for example, in a state where a part of the main subject has not yet entered the area of the image plane phase difference AF as shown in FIG. 7B. Sometimes it can be done.

  Note that switching determination from contrast AF to image plane phase difference AF is not limited to the determination method of this embodiment. For example, when contrast AF is performed, focus detection areas a to k of image plane phase difference AF are detected. If a predetermined time elapses after capturing a person's face in either case, the contrast AF may be switched to the image plane phase difference AF.

  When switching from the contrast AF to the image plane phase difference AF is determined, the process proceeds to step S18, where the phase difference AF circuit 7 executes the image plane phase difference AF and the calculation by the contrast AF circuit 6 is stopped. In the case where power is supplied to the contrast AF circuit 6 in step S10, the supply of power to the contrast AF circuit 6 may be stopped in step S18 to stop the contrast AF. Then, it returns to step 6 of FIG. 5 and repeats the process mentioned above.

  According to this embodiment, the focus detection pixels for performing the image plane phase difference AF are arranged in the central portion of the photographing screen and its periphery (near the central portion), and the photographing screen peripheral portion is substantially only the imaging pixels. It becomes. In this case, the raw image information cannot be obtained in the central portion of the shooting screen, but the image information does not deteriorate because the raw image information is obtained in the peripheral portion of the shooting screen. However, the central portion of the photographing screen is more advantageous in terms of aberration, incident light quantity, and the like than the peripheral portion of the photographing screen. For this reason, image information corresponding to the position of the focus detection pixel is obtained using a known interpolation process (for example, a known pixel defect correction technique) using the output of the imaging pixels around the position of the focus detection pixel. As a result, it is possible to minimize degradation of the image quality.

  In addition, when the subject movement is relatively small as in portrait photography, the contrast AF and the image plane phase difference AF are performed by switching between the contrast AF and the image plane phase difference AF. As compared with a conventional hybrid AF camera that executes the above simultaneously, the power consumption of the battery 14 accompanying the calculation can be suppressed.

  According to the hybrid AF camera of one embodiment, when the subject is focused on the center of the shooting screen and then the AF is followed by changing the composition, there is a human face on the periphery of the shooting screen from the beginning. Furthermore, in contrast AF, the focusing lens must be searched and driven over a wide range. In this embodiment, after performing coarse adjustment by image plane phase difference AF at the center of the shooting screen, the composition is changed and switched to contrast AF. Therefore, the time required for peak detection in contrast AF can be shortened. In particular, a function similar to the AF lock function in a single-lens reflex camera can be realized.

<Operation in tracking shooting mode>
<Second Embodiment>
Although the portrait mode has been described in the first embodiment, the AF operation can be switched in other shooting modes. In the second embodiment, the operation in the tracking shooting mode will be described using the description of the first embodiment.
In the tracking shooting mode, first, identification of a main subject is detected in a through image using a known subject recognition technique, for example, the above-described face recognition technique.
When the main subject recognized in the through image exists in the AF area of the image plane phase difference AF, AF is performed on the main subject using the image plane phase difference AF, and when the main subject exists in the AF area of the contrast AF. Performs AF on the main subject using contrast AF.
Next, a well-known tracking AF is performed on the main subject. At this time, when the main subject moves to the boundary area between the AF area of the image plane phase difference AF and the AF area of the contrast AF, the AF operation described above with reference to FIGS. .

<< Modification 1 of Embodiment 1 >>
In the embodiment described above, an example in which the image plane phase difference AF is stopped when the face area of the person deviates from the focus detection areas a to k of the image plane phase difference AF has been described. However, a method using this without stopping the image plane phase difference AF is also conceivable. Contrast AF is used to detect the focus on the person (face) around the shooting screen, which is the main subject, and the image plane phase difference is applied to the background located at the center of the shooting screen. It is also possible to perform focus detection by AF, determine an aperture that focuses on both the face and background of a person, and perform imaging.

  For example, as shown in FIG. 7C, the face of a person who has deviated from the focus detection areas a to k of the image plane phase difference AF is subjected to focus detection by contrast AF, and the focus detection area for Mt. Fuji in the background. Focus detection is performed by image plane phase difference AF at any one of a to k, and an image is picked up by determining an aperture that is in focus on both the face of the person and Mt. Fuji in the background. Alternatively, AF may be performed by focusing between the face of a person and Mt. Fuji in the background.

<< Modification 2 of Embodiment >>
In the above embodiment, the switching of the AF operation between the image plane phase difference AF and the contrast AF is determined according to the area where the main subject exists.
As another embodiment, the focus detection calculation is performed by the image plane phase difference AF at the target position X by the contrast AF, and the target position of the calculation result by the contrast AF and the target position of the calculation result by the image plane phase difference AF are calculated. If the difference is less than or equal to a preset reference value, the switching from the contrast AF to the image plane phase difference AF may be determined when the difference continues for a predetermined number of times.

<< Modification 3 of Embodiment >>
In the second modification, the output of the contrast AF circuit 6 at the time of transition is used as it is as the initial target position of the contrast AF when shifting to the image plane phase difference AF or contrast AF. As another embodiment, a method of setting the lens target position Xlast of the last image plane phase difference AF as the lens target position X of the first contrast AF is also conceivable.

  At the time of contrast AF control, an image at the target position X is first displayed, and the focusing lens is slightly moved between positions X−σ and X + σ before and after the target position X (referred to as search drive or wobbling), and three positions X− Contrast calculation is performed by imaging with σ, X, and X + σ. As a result of the contrast calculation, when the contrast at the position X is higher than the contrast at the previous and subsequent positions X−σ and X + σ, the focusing lens is moved to the target position X. When the contrast at the position X−σ or X + σ is high, a position having a high contrast is set as a new target position X, and the focusing lens is slightly moved between X−σ and X + σ before and after the position to set the position 3−X Contrast calculation is performed by imaging with −σ, X, and X + σ.

  When the focusing lens is slightly moved between the three positions X−σ, X, and X + σ to perform search driving in contrast AF, the images captured at the three positions X−σ, X, and X + σ are displayed on the monitor 10 each time. Instead of displaying as a through image, only the image captured at the target position X is displayed on the monitor 10 as a through image. As a result, it is possible to solve the problem that it is difficult to see the monitor screen because the through image display is frequently switched during contrast AF.

  In the above-described embodiments and their modifications, all combinations of the embodiments or the embodiments and the modifications are possible.

  According to embodiment mentioned above, there can exist the following effects. First, based on the positional relationship between the face area of the person who is the main subject and the focus detection area set at the center of the shooting screen, from the image plane phase difference AF to the contrast AF, or from the contrast AF to the image plane phase difference AF. Predict the switching. Then, after performing the calculation by the image plane phase difference AF or contrast AF of the switching destination, the image plane phase difference AF and the contrast AF are switched. The image plane phase difference AF and the contrast AF can be switched and executed.

  Further, according to the above-described embodiment, when the focus of the photographing lens is adjusted by the image plane phase difference AF, when the face area of the person moves to the end of the focus detection area, the image plane Switching from phase difference AF to contrast AF is predicted, and calculation by contrast AF is executed. As a result, the switching from the image plane phase difference AF in the focus detection area at the center of the shooting screen to the contrast AF at the periphery of the shooting screen can be reliably and smoothly performed.

  According to the above-described embodiment, when the human face area deviates from the focus detection area after execution of the contrast AF at the switching destination, the image plane phase difference AF is switched to the contrast AF, and the image plane position is changed. The calculation by phase difference AF was stopped. Therefore, any one of the image plane phase difference AF and the contrast AF can be rationally operated.

  According to the above-described embodiment, when switching from the image plane phase difference AF to the contrast AF, the target position of the last photographing lens based on the image plane phase difference AF is set as the target position of the contrast AF. Since the photographic lens is driven to search before and after the position to detect the position of the photographic lens at which the contrast reaches a peak, switching from the image plane phase difference AF to the contrast AF can be performed smoothly.

  According to the embodiment described above, when the focus of the photographing lens is adjusted by contrast AF, if the face area of the person is detected at the end of the focus detection area, the image plane position is determined from the contrast AF. Switching to phase difference AF is predicted, and calculation based on image plane phase difference AF is executed. Therefore, the switching from the contrast AF in the peripheral portion of the photographing screen to the image plane phase difference AF in the focus detection region in the central portion of the photographing screen can be surely and smoothly performed.

  According to the above-described embodiment, when the image plane phase difference AF at the switching destination is calculated, the contrast AF target position and the image plane phase difference AF target position satisfy a predetermined condition. While switching from AF to image plane phase difference AF, the calculation by contrast AF is stopped. Therefore, any one of the image plane phase difference AF and the contrast AF can be rationally operated.

  According to the above-described embodiment, the image plane position is detected from the contrast AF when the focus detection in which the difference between the target position of the contrast AF and the target position of the image plane phase difference AF is within a predetermined value is continuously generated a predetermined number of times. Since the switching to the phase difference AF and the contrast AF are stopped, the switching from the contrast AF to the image plane phase difference AF can be executed reliably and smoothly.

  According to the embodiment described above, the focus detection pixels are arranged in a line shape along the long side direction of the photographing screen 3a, but are arranged in a line shape along the short side direction of the photographing screen 3a. May be. In this case, the focus detection areas a to k are set in a line shape along the short side direction of the shooting screen 3a, and the focus detection pixels are short on the shooting screen 3a as shown by the hatched portion in FIG. They are arranged in a line-shaped region along the side direction. FIG. 4B is a partial enlargement showing the arrangement of the light receiving areas of the imaging pixels R, G, B and the focus detection pixels S3, S4 in the vertical (short-side direction of the photographing screen 3a) area of the focus detection area. FIG.

  In FIG. 4B, as in the case of FIG. 3B, each “mass” surrounded by vertical and horizontal lines indicates an imaging pixel region. A square indicated by a solid line in each square indicates a mask opening, and indicates a light receiving area of each pixel through which the light reaches the light receiving part. Further, in FIG. 4B, as in FIG. 3B, the area surrounded by the semicircle indicates the mask opening of the focus detection pixel, and the light is received through the mask opening. The light receiving area of each pixel that reaches is shown. R, G, and B represent an imaging red pixel, an imaging green pixel, and an imaging blue pixel, respectively. In FIG. 4B, illustration of the microlens and the light receiving portion of each pixel is omitted. In addition, in the vertical pair of focus detection pixels S3 and S4 shown in FIG. 4B, the light receiving region is arranged so as to be biased upward and downward with respect to the pixel center.

  In the example shown in FIG. 4B, in the vertical region of the focus detection region, the focus detection pixels S3 and S4 are paired, and the focus adjustment state in the vertical direction of the photographing lens 2 (the short side direction of the photographing screen 3a) is changed. A focus detection signal is output. When the focus detection pixels are arranged as described above, the phase difference AF circuit 7 determines the focus adjustment state of the focusing lens based on the focus detection signals output from the pair of focus detection pixels (S3, S4). Is calculated.

  The focus detection areas a to k may be set in a cross shape. In this case, the array of focus detection pixels shown in FIG. 3B may be combined with the array of focus detection pixels shown in FIG.

DESCRIPTION OF SYMBOLS 1; Hybrid AF camera, 2; Shooting lens, 3; Image pick-up element, 5; Image processing circuit, 6: Contrast AF circuit, 7: Phase difference AF circuit, 8; Lens drive circuit, 10; Monitor, 15; , G, B; imaging pixels, S1 to S4; focus detection pixels, a to k; focus detection regions

Claims (8)

  1. An imaging device in which imaging pixels and focus detection pixels are two-dimensionally arranged on an imaging surface, wherein the imaging pixels are arranged over the entire imaging surface, and are set to a part of the imaging surface. An image sensor in which the focus detection pixels are arranged in the focus detection area;
    An imaging optical system that forms a subject image on the imaging surface of the imaging element;
    First focus adjustment means for performing focus adjustment of the photographing optical system by a phase difference detection method based on an output signal of the focus detection pixel;
    Second focus adjusting means for performing focus adjustment of the photographing optical system by a contrast method based on an output signal of the imaging pixel;
    Image processing means for recognizing a main subject by processing an image picked up by the image pickup device;
    Based on the positional relationship between the main subject recognized by the image processing means and the focus detection area, one focus adjustment means from the first focus adjustment means and the second focus adjustment means to the other focus. Switching prediction means for predicting switching to the adjusting means;
    An activation unit that activates the other focus adjustment unit that is a switching destination when switching is predicted by the switching prediction unit;
    A camera comprising: switching means for switching from the one focus adjustment means to the other focus adjustment means after activation of the other focus adjustment means to be switched by the activation means.
  2. The camera of claim 1,
    The switching predicting means, when the focus adjustment is performed by the first focus adjusting means, when the main subject moves to the end of the focus detection area, A camera characterized by predicting switching to a bifocal adjustment means.
  3. The camera according to claim 2,
    The switching means switches from the first focus adjustment means to the second focus adjustment means when the main subject deviates from the focus detection area after activation of the second focus adjustment means to be switched by the activation means. A camera characterized by switching and stopping the operation of the first focus adjusting means.
  4. The camera according to claim 3.
    At the time of switching from the first focus adjustment means to the second focus adjustment means, the last target position of the photographing optical system by the first focus adjustment means is set to the first target position of the second focus adjustment means, 2. The camera according to claim 1, wherein the second focus adjusting unit detects the position of the photographing optical system at which the contrast reaches a peak by performing search driving of the photographing optical system before and after the target position.
  5. The camera of claim 1,
    When the focus adjustment of the photographing optical system is being performed by the second focus adjustment unit, the switching prediction unit is configured to detect the second focus when the main subject is detected at the end of the focus detection region. A camera for predicting switching from the adjusting means to the first focus adjusting means.
  6. The camera according to claim 5, wherein
    The switching means, when the target position of the second focus adjusting means and the target position of the first focus adjusting means satisfy a predetermined condition after the start of the first focus adjusting means of the switching destination by the starting means And switching from the second focus adjusting means to the first focus adjusting means and stopping the operation of the second focus adjusting means.
  7. The camera according to claim 6, wherein
    The predetermined condition is a case where focus detection in which a difference between a target position of the second focus adjusting unit and a target position of the first focus adjusting unit is within a predetermined value is continuously generated a predetermined number of times. Camera.
  8. In the camera according to any one of claims 1 to 6,
    Display means for displaying an image captured by the imaging means;
    The display means is configured to detect the position of the imaging optical system at the target position when the second focus adjustment means detects and drives the imaging optical system before and after the target position to detect the position of the imaging optical system. A camera characterized in that an image picked up by (2) is displayed on a display means.
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