JP2007228007A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital camera of a bent optical system for achieving automatic framing. <P>SOLUTION: A mirror 210 for bending incident light onto an imaging element is supported turnably around the X revolving axis and the Z revolving axis. A first actuator 311 is driven to revolve the mirror 210 around the X revolving axis. Further, a second actuator 321 is driven to revolve the mirror 210 around the Z revolving axis. Thus, an imaged image can be moved in both longitudinal and lateral directions. When tracking framing function is in use, an object takes a prescribed position through automatic framing without moving a camera main body by revolving the mirror 210 so that the object position on the imaged image takes the prescribed position at all times (e.g., in the middle of the image). Thus, the digital camera of a bent optical system can be focused without causing a camera shake and an image shake while executing framing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a digital camera, and more particularly to a bending optical digital camera.

  2. Description of the Related Art Conventionally, there has been known a digital camera that bends incident light and forms an image on an image sensor (for example, Patent Document 1). In such a bent optical type digital camera, a lens unit or the like can be configured in the main body. For example, unlike a digital camera having a retractable lens, the lens is projected outside the main body of the digital camera. In addition, since the zoom function and the autofocus function can be realized, a compact digital camera with a flat outer surface can be realized.

Further, in cameras having an auto focus (AF) function, tracking AF (continuous AF) is known in which a moving subject is focused at any time. By such tracking AF, for example, an approaching subject can be easily focused and photographed.
JP 2004-219516 A

  However, with conventional tracking AF, it is possible to focus on a subject at a predetermined position at any time. For this purpose, the photographer needs to adjust the position and angle of the camera so that the subject is always at the predetermined position. There is.

  Since the above-described bent optical digital camera is small and lightweight, when the camera body is moved, the movement greatly affects the captured image. Therefore, when the tracking AF function is used with such a bending optical digital camera, camera shake and image blur are likely to occur due to the operation for making the subject position constant.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a bending optical digital camera capable of appropriately capturing an image of a moving subject without causing blurring.

In order to achieve the above object, a digital camera according to the first aspect of the present invention provides:
In a digital camera that obtains a captured image by imaging incident light bent by a reflector on an image sensor,
Drive means for rotationally driving the reflector;
Subject image detection means for continuously detecting a subject image shown at an arbitrary position designated on the captured image;
Subject tracking means for controlling the driving means and rotating the reflector so that the subject image detected by the subject image detection means is at a predetermined position on the captured image;
It is characterized by providing.

  According to such a configuration, the reflector (mirror) used in the bending optical digital camera is rotated to follow the subject, so that the subject is automatically set to a predetermined position without moving the camera body. Can be framing. In this case, since the camera body does not move, camera shake and image blur can be prevented.

The above digital camera
An autofocus means for performing an autofocus operation based on parameters obtained from the captured image;
Focusing determination means for determining whether or not the captured image at the arbitrary position is in focus based on an autofocus operation by the autofocus means;
When the captured image at the arbitrary position is not in focus, it is preferable to further include a focus position search unit that searches for a position on the captured image that is focused by the autofocus operation.
The subject image detection means preferably detects the subject image by designating the position searched by the in-focus position search means as the arbitrary position.

  According to such a configuration, for example, the position of the subject is specified based on a plurality of focus frames used in multipoint AF or the like, and another position that is in focus when the focus stops at that position is searched. To do. Then, by setting the searched position as the subject position, the moving subject can be followed and focused at any time.

The above digital camera
The image processing apparatus may further include a feature extraction unit that extracts a feature of the image at the arbitrary position.
Preferably, the subject image detection means detects the subject image by designating a position of an image showing the same or similar feature as the feature extracted by the feature extraction means as the arbitrary position.

  According to such a configuration, by extracting the feature of the subject image, it is possible to follow the position indicating the feature that is the same or similar to the feature on the captured image as the subject moving position at any time.

The above digital camera
It may further comprise a vector detection means for detecting a movement vector between a plurality of frames of the image at the arbitrary position.
The subject image detection means preferably detects the subject image by designating the arbitrary position based on the movement vector detected by the vector detection means.

In addition, the digital camera
Based on the detection history of the subject image by the subject image detection means, it may further comprise subject image prediction means for predicting the movement position of the subject image.
It is desirable that the subject image detection means detects the subject image by designating the position predicted by the subject image prediction means as the arbitrary position.

  According to such a configuration, it is possible to calculate the movement vector from the change between the frames of the subject image, and to predict and follow the next movement position of the subject image based on the movement vector.

In the above digital camera,
The subject image detection means can detect the subject image based on the arbitrary position specified by a plurality of focus frames set on the captured image.

  According to such a configuration, it is possible to easily follow the subject using the focus frame used in so-called multipoint AF.

In the above digital camera,
The driving means includes
First rotating means for rotating the reflector in a vertical direction on the captured image;
It is desirable to further comprise second rotating means for rotating the reflector in the lateral direction on the captured image.
The subject tracking means preferably controls the first rotating means and the second rotating means to rotate the reflector so that the subject image is at a predetermined position on the captured image.

  According to such a configuration, the reflector (mirror) used in the bending optical digital camera can be rotated in the biaxial direction, so that the captured image is displayed in the vertical direction and in accordance with the movement of the subject. It is possible to follow the subject by moving it horizontally.

In the above digital camera,
The subject tracking means may rotate the reflector so that the subject image is at the center position of the captured image.

  According to such a configuration, it is possible to automatically follow the subject so that the subject is always at the center position of the captured image.

  According to the present invention, it is possible to automatically perform framing so that the subject is in a predetermined position without moving the camera body by rotating the reflector used in the bending optical digital camera.

  Embodiments according to the present invention will be described below with reference to the drawings. In the present embodiment, the case where the present invention is applied to a digital still camera having at least an auto focus (AF) function will be described as an example.

  An external configuration of the digital camera 100 according to the present embodiment will be described with reference to FIG. FIG. 1 is a view showing an example of the appearance of a digital camera 100 according to the present embodiment (FIG. 1 (a) is a front view and FIG. 1 (b) is a rear view).

  As shown in FIG. 1A, an entrance window 10, a photometric unit 120, and the like are configured on the front surface of the digital camera 100. As shown in FIG. 1B, on the back of the digital camera 100, for example, a zoom button 132, a mode changeover switch 133, a cross key 134, a button group 135, and the like are configured as the operation unit 130. A shutter button 131 is configured on the upper surface of the digital camera 100. A display unit 140 is configured on the back of the digital camera 100.

  The incident window 10 includes an opening provided to allow light indicating an imaging target (subject) to enter the inside of the digital camera 100 and a transparent member that covers the opening when the image is captured by the digital camera 100. .

  The photometry unit 120 is composed of a photometry device that is generally used for an ordinary camera having an auto focus (AF) function or an auto exposure (AE) function. Detection is performed.

  The shutter button 131 is a button for performing an operation related to the imaging operation of the digital camera 100. That is, it has the same function as a shutter button in a normal still camera. For example, AF and AE operations are performed when half-pressed, and shutter operation is performed when fully pressed.

  The zoom button 132 is a button for operating the zoom function of the digital camera 100.

  The mode changeover switch 133 is constituted by, for example, a slide-type switch, and is used for changing a plurality of operation modes of the digital camera 100. In this embodiment, it is used for AF mode switching or the like.

  The cross key 134 is a key for performing various input operations by the user, and includes a left direction key, a right direction key, an up direction key, and a down direction key.

  The button group 135 is a button for operating various functions of the digital camera 100. For example, a menu button for displaying a menu screen on the display unit 140 and display / non-display of the display unit 140 are selected. Used as a display button, etc.

  The display unit 140 is composed of, for example, a liquid crystal display device, and displays a subject image and a captured image at the time of shooting. In addition, various screens used when executing various functions of the digital camera 100 are displayed.

  The digital camera 100 according to the present embodiment is a so-called bending optical digital camera that bends incident light to form an image on an image sensor. The optical unit 200 for realizing such a bending optical system is configured at a position indicated by a broken line in FIG. That is, it is configured at a position corresponding to the entrance window 10 configured in the front part of the digital camera 100.

  The configuration of the optical unit 200 will be described with reference to FIG. 2B is a side view of the digital camera 100 shown in FIG. 2A (the left side is shown from the back side of the digital camera 100), and an optical unit configured inside the digital camera 100. FIG. A configuration of 200 is schematically shown. As shown in the figure, the optical unit 200 mainly includes a mirror 210, a lens unit 220, an image sensor 230, and the like.

  The mirror 210 is a mirror (reflector) for bending incident light that has entered from the incident window 10 and is inclined at a position corresponding to the incident window 10 as shown in FIG. . As a result, the incident light that has entered the incident window 10 is bent downward in the digital camera 100.

  The lens unit 220 includes a plurality of lens groups, and the subject light bent by the mirror 210 passes through the lens unit 220.

  The image pickup device 230 is composed of, for example, a photoelectric conversion device such as a CCD (Charge Coupled Device), receives the subject light bent by the mirror 210 and transmitted through the lens unit 220, and corresponds to the amount of light received. Captured image data is generated by generating an electrical signal. The image sensor 230 includes a predetermined ADC (Analog-Digital Converter), and digital data of the captured image is generated by digitally converting the generated electrical signal. .

  As shown in FIG. 2B, in the present embodiment, the image sensor 230 is disposed in the vicinity of the bottom surface of the digital camera 100 at a position where the light receiving surface faces the upper direction of the digital camera 100 and is parallel to the bottom surface. Is done. In this case, the mirror 210 is tilted at an angle at which the bent incident light is perpendicularly incident on the image sensor 230. In the present embodiment, since the incident light is bent in the vertical direction of the digital camera 100, the narrow angle formed by the optical axis of the subject light perpendicular to the front of the digital camera 100 and the reflecting surface of the mirror 210 is 45 ° or substantially. The mirror 210 is arranged with an inclination of 45 °. This angle is hereinafter referred to as “reference angle”.

  A detailed configuration of the optical unit 200 will be described with reference to FIG. FIG. 3 is a perspective view illustrating a configuration example of the optical unit 200. As shown in the figure, the optical unit 200 includes a mirror 210, a lens unit 220, and an image sensor 230 on a pedestal 201.

  The mirror 210 according to the present embodiment is configured to be rotatable, and is installed on the base 201 in a state of being housed in a mirror unit 300 for rotating the mirror 210. The configuration of the mirror unit 300 will be described later.

  The lens unit 220 includes a focusing lens 220a, a zoom lens 220b, an optical operation unit 221, a lens support 222, a lens driving unit 223, and the like.

  The focus lens 220a and the zoom lens 220b are movable lenses held by the lens support 222, and each move in a direction indicated by a double arrow in the drawing. Here, the lens support 222 includes a support 222a that indicates one end of the focus lens 220a, a support 222b that indicates one end of the zoom lens 220b, and each of the focus lens 220a and the zoom lens 220b. It is comprised from 222c which designates the other end. The support body 222a and the support body 222b include, for example, a rack and pinion mechanism. Each of the support body 222a and the support body 222b is rotationally driven by, for example, a lens driving unit 223 including a motor and a gear. By this operation, the focus lens 220a and the zoom lens 220b move.

  Here, the focus lens 220 a operates by an AF function based on the operation of the photometry unit 120. The zoom lens 220b is operated by operating the zoom button 132.

  The optical operation unit 221 includes, for example, a fixed lens, a diaphragm blade, a shutter mechanism, and the like. The optical operation unit 221 forms an image of subject light transmitted through the focus lens 220a and the zoom lens 220b on the image sensor 230 and has a set exposure. Shutter operation is performed with a diaphragm according to the above.

  Next, the configuration of the mirror unit 300 shown in FIG. 3 will be described with reference to FIG. 4A is a plan view of the mirror unit 300 viewed from the incident window 10 side, and FIG. 4B is a side view corresponding to FIG. 4A illustrates the mirror unit 300 viewed from the front of the digital camera 100, and FIG. 4B illustrates the mirror unit 300 viewed from the left side when viewed from the back side of the digital camera 100. Yes.

  As illustrated, the mirror unit 300 includes a pedestal 301, a first holding body 310, a first actuator 311, a fixed support body 312, a movable support body 313, a second holding body 320, a second actuator 321, and the like. Consists of

  The first holding body 310 covers the back surface of the mirror 210 (the back side of the reflection surface) and holds the mirror 210 so that the reflection surface of the mirror 210 is exposed. The first holding body 310 holding the mirror 210 in this way is held by the second holding body 320.

  In this case, the first holding body 310 is a so-called gimbal that is held by the second holding body 320 so as to be rotatable about the X-X ′ axis shown in FIG. That is, the mirror 210 held by the first holding body 310 is held so as to be rotatable about the X-X ′ axis. Here, the X-X ′ axis (hereinafter referred to as “X rotation axis”) is the central axis of the mirror 210 parallel to the longitudinal direction of the mirror 210. More specifically, as shown in FIG. 5, when the digital camera 100 is horizontally installed so that the shutter button 131 is on the upper surface, the digital camera orthogonal to the optical axis of the incident light perpendicularly incident on the front of the digital camera 100 100 horizontal axes.

  As shown in FIG. 4B, the second holding body 320 has a shape in which the upper portion protrudes toward the incident window 10 side. By being held by the second holding body 320 having such a shape, the first holding body 310 holds the mirror 210 so that the mirror 210 has a reference angle.

  The first actuator 311 and the second actuator 321 are actuators for rotating the mirror 210 held by the first holding body 310 and the second holding body 320, and generate a linear motion, for example. Consists of a voice coil motor. As shown in FIG. 4A, the first actuator 311 is fixed to the pedestal 301 so as to generate a linear motion in a direction parallel to the ZZ ′ axis in the figure, and the second actuator 321 It is fixed to the pedestal 301 so that a linear motion is generated in a direction parallel to the X rotation axis.

  In this case, as indicated by a double arrow ZA-ZA ′, the first actuator 311 generates a linear motion in both directions with respect to the X rotation axis. The second actuator 321 generates linear motion in both directions with reference to the Z-Z ′ axis, as indicated by a double arrow XA-XA ′. Here, as shown in FIG. 5, the Z-Z ′ axis is an axis parallel to the vertical axis of the digital camera 100 when the digital camera 100 is horizontally installed so that the shutter button 131 is on the upper surface.

  Then, as shown in FIG. 4B, the second holding body 320 is held on the base 301 so as to be rotatable around a ZZ ′ axis (hereinafter referred to as “Z rotation axis”). It is a so-called gimbal. More specifically, the second holding body 320 is rotatably held by the upper stay 301a and the lower stay 301b that protrude perpendicularly from the pedestal 301 in the direction of the entrance window 10.

  The linear motion generated by the first actuator 311 acts on the first holding body 310 via the fixed support body 312 and the movable support body 313. Here, as shown in FIG. 4A, the fixed support body 312 is, for example, a substantially prismatic support body, one end of which is fixed to the movable portion of the first actuator 311, and from the first actuator 311. Projecting to the back of the mirror 210. In this case, the position where the longitudinal center line of the fixed support 312 matches the X-X ′ axis is the reference position of the first actuator 311. As the first actuator 311 is driven, the fixed support 312 is also moved in the vertical direction (the direction of the double arrow ZA-ZA ′ shown in FIG. 4A).

  Further, as shown in FIG. 4B, the movable support 313 has a substantially rod shape, one end is fixed to the first holding body 310, and the other end is connected to the fixed support 312 so as to be rotatable. Has been. When the first actuator 311 is in the reference position, the movable support 313 has a longitudinal center line parallel to the horizontal axis of the digital camera 100 orthogonal to the X-X ′ axis. Here, as shown in FIG. 4B, the cross section of the fixed support 312 at the connection portion with the movable support 313 has a substantially U shape with an opening on the mirror 210 side. The end of the movable support 313 having a substantially spherical shape as shown in FIG. 4B is connected to such a U-shaped opening. In other words, such a substantially spherical end is engaged with the opening of the fixed support 312 so as to be pivotally connected. In this case, when the first actuator 311 is at the reference position, the angle between the movable support 313 and the fixed support 312 as viewed from the side is substantially a right angle as shown in FIG. Since the fixed support 312 and the movable support 313 are connected in this way, the movable support 313 and the fixed support 312 as viewed from the side according to the vertical movement of the fixed support 312 by the first actuator 311. The angle with will change.

  The other end of the movable support 313 is fixed to the first holding body 310 at a position corresponding to the center position of the mirror 210. As described above, since the first holding body 310 is held by the second holding body 320 so as to be rotatable around the XX ′ axis, the fixed support body 312 is moved according to the vertical movement of the fixed support body 312. When the angle changes, the first holding body 310 rotates in the direction of the double-headed arrow aa ′ in FIG. That is, the mirror 210 held by the first holding body 310 rotates around the X-X ′ axis by the operation of the first actuator 311.

  On the other hand, the linear motion generated by the second actuator 321 acts on the second holding body 320. In this case, since the second holding body 320 is held so as to be rotatable about the Z rotation axis, the linear movement generated by the second actuator 321 in the X rotation axis direction is held in the second direction. By acting on the body 320, the second holding body 320 rotates about the Z rotation axis. In this case, the first holding body 310 held by the second holding body 320 rotates around the Z rotation axis. Since the mirror 210 is held by the first holding body 310, the mirror 210 is rotated around the Z rotation axis by the operation of the second actuator 321.

  Here, in a so-called following AF (continuous AF) realized in a camera having a conventional AF function, for example, a subject that approaches the camera by autofocusing so that the moving subject is always in focus. It is possible to focus automatically on the subject, so that the photographer can focus on the composition and the photo opportunity without being aware of the focus.

  In such tracking AF, in order to always focus the subject, the subject needs to be at a certain position on the captured image. Therefore, when shooting with tracking AF, it is necessary for the photographer to always adjust the camera position so that the subject is in a predetermined position.

  In particular, in the case of a lightweight and small camera that employs a bending optical system, such as the digital camera 100 according to the present embodiment, the camera is easily affected by the movement of the photographer's hand. Therefore, the adjustment of the camera position required when shooting with tracking AF becomes a cause of camera shake and image blur.

  Therefore, in this embodiment, the mirror 210 is rotated as described above to perform the framing operation so that the moving subject is always at a predetermined position on the captured image. That is, if the mirror 210 rotates about the X rotation axis, the incident light imaged on the image sensor 230 changes in the vertical direction of the captured image, and if the mirror 210 rotates about the Z rotation axis, the imaging is performed. Since the incident light imaged on the element 230 changes in the horizontal direction of the captured image, the angle of the captured image can be changed without moving the main body of the digital camera 100. By using such an operation and changing the angle according to the movement of the subject image, it is possible to perform framing so that the subject image is always at a predetermined position on the captured image.

  In this embodiment, as shown in FIGS. 4 and 5, the operation of rotating the mirror 210 about the X rotation axis to change the captured image in the vertical direction is hereinafter referred to as “tilt rotation”. Hereinafter, the operation of rotating around the X rotation axis to change the captured image in the horizontal direction is referred to as “pan rotation”. In this embodiment, a mode in which framing is performed so that the subject image becomes a fixed position by such tilt rotation or pan rotation, and autofocus is performed so that the subject image is always in focus. “Follow-up framing mode”.

  Next, the internal configuration of the digital camera 100 will be described with reference to FIG. FIG. 6 is a block diagram showing an internal configuration of the digital camera 100. As illustrated, the digital camera 100 according to the present embodiment includes a control unit 110 that controls the above-described photometric unit 120, operation unit 130, display unit 140, optical unit 200, image sensor 230, mirror unit 300, and the like. A storage unit 150 is provided.

  The control unit 110 includes, for example, a CPU (Central Processing Unit) and a memory (register, RAM (Random Access Memory), etc.) serving as a work area, and controls each unit of the digital camera 100. In addition, each process described later is realized by executing a predetermined operation program.

  The storage unit 150 includes a storage device such as a ROM (Read Only Memory) or a flash memory, for example, and stores various data necessary for executing the operation of the digital camera 100. In this embodiment, as shown in FIG. 6, storage areas such as a captured image storage area 151 and a program storage area 152 are created in the storage unit 150, and predetermined information is stored in each storage area.

  The captured image storage area 151 stores image data indicating an image captured by the digital camera 100. The captured image storage area 151 may be configured as a removable storage device (such as a memory card) that can be attached to and detached from the digital camera 100.

  The program storage area 152 stores an operation program executed by the control unit 110. When the control unit 110 executes the operation program stored in the program storage area 152, the control unit 110 realizes functions as shown in the functional block diagram of FIG. That is, the control unit 110 functions as the imaging processing unit 111, the image processing unit 112, the tracking processing unit 113, the optical system processing unit 114, and the like by executing the program.

  The imaging processing unit 111 performs an imaging operation by driving and controlling the optical unit 200 and the imaging element 230.

  The image processing unit 112 performs predetermined image processing (for example, data compression processing) on the captured image data generated by the imaging element 230 under the control of the imaging processing unit 111, and displays the image data on the display unit 140. And stored in the captured image storage area 151.

  The follow-up processing unit 113 controls the mirror unit 300 to perform a follow-up framing operation in which the mirror 210 is panned or tilted to perform framing so that the subject image is at a predetermined position on the captured image.

  The optical system processing unit 114 controls the optical unit 200 based on the captured image data from the image processing unit 112, thereby performing an AF operation that always focuses on the subject image tracked by the tracking processing unit 113.

  In the present embodiment, the above-described functional configuration is logically realized by the control unit 110 executing a program. These functions are, for example, ASIC (Application Specific Integrated Circuit) or the like. It may be configured by hardware.

  Note that each of the above configurations is a configuration necessary for realizing the present invention, and other configurations required for realizing a basic function and an additional function as a digital camera are digital as necessary. It is assumed that the camera 100 is provided.

  The operation of the digital camera 100 configured as described above will be described below. Here, a case where a moving subject is still photographed in the following framing mode according to the present embodiment will be described as an example. An imaging process executed by the digital camera 100 in this case will be described with reference to a flowchart shown in FIG. This imaging process is started when the follow-up framing mode is selected.

  When the processing is started, the image sensor 230 is operated under the control of the imaging processing unit 111, and incident light is displayed on the display unit 140 as needed by the image processing unit 112. In this state, the image processing unit 112 displays a plurality of focus frames on the display unit 140 (step S101). A display example of the focus frame is shown in FIG. As shown in the drawing, it is assumed here that the square focus frames are arranged 3 × 3 on the captured image displayed on the display unit 140. It is assumed that the focus frame is displayed so that the centers of the plurality of focus frame groups coincide with the center of the captured image (= finder screen).

  Such a focus frame is the same as the focus frame used in so-called multipoint AF, which has been realized in the conventional AF field. In the case of normal multipoint AF, for example, when the user operates a cross key or the like to designate one of the focus frames and press the shutter halfway, the AF operation is performed so that the designated focus frame portion is focused. It is carried out.

  In the present embodiment, the focus frame to be focused in this way is defined in advance, and the image processing unit 112 automatically designates it as a default. Here, the center frame of the 3 × 3 focus frame is designated as a focus target by default (step S102). As shown in FIG. 11A, the designated focus frame is displayed on the display unit 140 so as to be distinguished from other focus frames by, for example, blinking display.

  That is, in this embodiment, it is assumed that the position of the center focus frame, that is, the center position of the captured image is set by default so as to be a focus target. In this case, the photographer adjusts the position and angle of the digital camera 100 or the photographing position so that the subject to be photographed is displayed at the center of the screen. Then, when the subject is displayed at the center of the screen, the tracking and focusing operations in the tracking framing mode are started by pressing the shutter button 131 halfway.

  In this case, when an input signal indicating a half-press is input from the shutter button 131 to the control unit 110 (step S103: Yes), the optical system processing unit 114 executes AF processing (step S200). This AF process will be described with reference to the flowchart shown in FIG.

  When the processing is started, the optical system processing unit 114 first determines whether or not the tracking operation for the designated frame is the first time in the imaging in the current tracking framing mode (step S201). In this case, the determination is made based on a predetermined flag (hereinafter referred to as “designated frame flag”) that is turned on when the operation for the designated frame is executed. For example, this designated frame flag is set in the work area or the like when the follow-up framing mode is selected.

  Here, since the operation for the focus frame specified in step S102 has not been executed yet, the specified frame flag is OFF. Therefore, the optical system processing unit 114 determines that it is the first time (step S201: Yes). In this case, the optical system processing unit 114 turns on the designated frame flag (step S202), and controls the lens driving unit 223 of the optical unit 200, so that the focusing lens 220a is positioned at the extreme end position of the movable range of the focusing lens 220a. An initialization operation is performed to move (step S203).

  When the lens position is initialized in this way, the optical system processing unit 114 notifies the image processing unit 112 of that fact and lens position information indicating the current lens position. In response to the notification from the optical system processing unit 114, the image processing unit 112 extracts an image in the center frame designated by default from the captured image obtained at the current lens position (step S204). A high-frequency component is extracted by performing band pass filter processing on the image data (step S205).

  The image processing unit 112 further calculates the focus evaluation value of the image by, for example, integrating the extracted high-frequency component (step S206). The image processing unit 112 records the calculated focus evaluation value and the lens position information notified from the optical system processing unit 114 in association with each other in the work area (step S207).

  When the focus evaluation value is recorded in the work area, the image processing unit 112 determines whether or not there is a previously recorded focus evaluation value (step S208). Here, since the focus evaluation value is calculated for the first time after the AF process is started, there is no focus evaluation value recorded last time (step S208: No). In this case, the image processing unit 112 instructs the optical system processing unit 114 to move the lens.

  The optical system processing unit 114 controls the lens driving unit 223 of the optical unit 200 in accordance with an instruction from the image processing unit 112, and the focusing lens 220a moves to a predetermined unit toward the other end position of the movable range. It is moved by the moving amount (step S210). If the position of the focus lens 220a does not reach the other extreme end position due to this movement (step S211: No), the optical system processing unit 114 indicates the lens position indicating the position of the focus lens 220a after the movement. Information is notified to the image processing unit 112.

  In this case, the image processing unit 112 records the lens position and the focus evaluation value in the work area in association with the captured image acquired at the moved lens position by performing the processing of Step S204 to Step S207. To do. By repeating such an operation until the focusing lens 220a reaches the other end position, the focusing lens 220a is moved by a predetermined unit movement amount for each position of the focusing lens 220a within the designated focus frame. Focus evaluation values for images are sequentially recorded in the work area.

  In this manner, the lens is moved by a predetermined unit movement amount, and a plurality of focus evaluation values calculated at the respective positions are recorded in the work area. Therefore, in the second and subsequent operations, it is determined that “the previous evaluation value exists” in the determination in step S208 (step S208: Yes). In this case, the image processing unit 112 determines whether or not the focus evaluation value calculated in step S206 is greater than the previously calculated focus evaluation value (that is, the focus evaluation value before moving the lens). (Step S209). If the focus evaluation value has increased (step S209: Yes), the lens is further moved (step S210). If the focus evaluation value has not increased (step S209: No), the process ends.

  By such an operation, the lens is moved until the focus evaluation value reaches a peak. That is, since the lens is sequentially moved from the extreme end, the focus value calculated in the process changes in a parabolic shape. Here, if it is higher than the previous calculated value, it means that it is going to the peak of the parabola or has reached the peak, and if it does not increase from the previous calculated value, it means that the peak has been exceeded. Become. Therefore, when the current calculated value has not increased from the previous calculated value (step S209: No), the lens is not moved by terminating the process. In this case, since the previous calculated value is the peak value, the lens stops at the position where the calculated value is obtained. That is, focusing is performed at the lens position. As a result, the image of the designated focus frame (that is, the position of the center frame) is focused. Here, as shown in FIG. 11B, since the AF operation is started with the subject (the person in the figure) at the center, the photographer focuses on the desired subject.

  On the other hand, if the current calculated value is greater than the previous calculated value (step S209: Yes), the lens is moved (step S210), and the moved lens position is not the other end position that is the end. (Step S211: No) By performing the processing of Step S204 to Step S207, the lens movement and the focus evaluation value are calculated until the peak value appears. Here, when the lens position has reached the end without the peak value appearing (step S211: Yes), the in-focus state cannot be achieved. This is a focusing failure caused by, for example, the contrast of the portion being weak. In this case, the process returns to step S203 to initialize the lens position and restart the AF operation.

  In the AF process immediately after the shutter button 131 is half-pressed, the subject is located in the center frame that is the focus target, so that the subject is focused by the AF operation at that position. When the subject is focused in this manner, the flow returns to the imaging processing flow shown in FIG. Here, when the image in the designated frame is in focus by the AF process (step S104: No), the AF process in the designated focus frame is repeatedly executed until the shutter button 131 is fully pressed (step S105: No). The second and subsequent AF processes will be described again with reference to the flowchart of FIG.

  Since the designated flag frame is turned on in step S202 in the first process, it is determined in step S201 in the second and subsequent AF processes that the designated frame flag is not turned off (step S201: No). In this case, the optical system processing unit 114 calculates the focus evaluation value for the image of the designated frame by the same processing as in steps S204 to S206 (step S212), and the calculated focus evaluation value and the previous operation time. The peak value recorded in step S207 is compared.

  Here, if the subject has not moved, focusing is performed at the same lens position. In this case, the focus evaluation value calculated this time and the peak value recorded last time are the same (step S213: No). In this case, the AF processing is terminated as it is, and the flow returns to the imaging processing flow shown in FIG.

  On the other hand, as shown in FIG. 11C, when the subject is moving, the subject may deviate from the position of the center frame specified first. At this time, since the in-focus state is not maintained at the lens position when initially focused, the focus evaluation value at the position is different from the previous peak value. Therefore, when the focus evaluation values for the same designated frame are different (step S213: Yes), the optical system processing unit 114 determines that focusing cannot be performed at the position (step S214), and the imaging process illustrated in FIG. Return to the flow.

  In the flow of the imaging process, the follow-up processing unit 113 determines whether or not it has been focused by the immediately preceding AF process (step S104). That is, when it is determined that focusing cannot be performed in step S214 of the AF process (FIG. 9), it is determined that focusing is not possible (focusing NG) (step S104: Yes).

  When the focus frame that can be focused on for the first time can no longer be focused, it is considered that the subject is moving, so the tracking processing unit 113 performs a tracking framing process for tracking and framing the subject (step). S300). The following framing process will be described with reference to the flowchart shown in FIG.

  When the process is started, the tracking processing unit 113 determines whether or not the tracking operation is the first time (step S301). Here, since the follow-up operation has not been performed yet, it is determined that the operation is the first operation (step S301: Yes). In this case, as shown in FIG. 12A, the tracking processing unit 113 sequentially specifies the frames around the focus frame (that is, the central frame) specified in step S102 of the imaging process (step S302), and each focus The optical system processing unit 114 is instructed to perform the AF operation with the frame. The optical system processing unit 114 performs a process similar to that in steps S203 to S210 of the AF process for each focus frame in accordance with an instruction from the tracking processing unit 113, so that the focus frame that may be in focus is obtained. Search for. The optical system processing unit 114 acquires the lens position when the focus evaluation value reaches a peak for each focus frame, and notifies the tracking processing unit 113 of the lens position.

  Here, for example, when the peak of the focus evaluation value is not obtained in any of the focus frames, the image processing unit 112 determines that there is no focus frame that may be in focus (step S304: No). In this case, the process returns to step S302, and the AF operation in each focus frame is executed again.

  On the other hand, when the focus evaluation value peak is obtained in any of the focus frames, the image processing unit 112 determines that there is a focus frame that may be in focus (step S304: Yes). In this case, when there are a plurality of focus frames with the possibility of focusing (step S305: Yes), the follow-up processing unit 113 is based on the lens position notified from the optical system processing unit 114, for example, has the longest focusing distance. A close focus frame is designated as a focusing frame (step S306). On the other hand, if there is only one focus frame that may be in focus (step S305: No), the focus frame is designated as the focus frame. In this way, as shown in FIG. 12B, a focus frame (frame highlighted in the figure) corresponding to the moved subject is designated.

  In this way, when a focus frame different from the center frame is designated as a new focusing frame, the follow-up processing unit 113 performs framing by pan / tilt operation so that the image corresponding to the focusing frame becomes the center of the image ( Step S307). That is, as shown in FIG. 12C, the mirror unit 300 is controlled based on the direction and distance between the default center frame and the new focusing frame, and the mirror 210 is rotated by panning and tilting. Then, framing is automatically performed so that the subject image at the newly designated position (that is, the position of the focusing frame) becomes the center of the captured image.

  The follow-up processing unit 113 records the amount and direction of pan / tilt movement at this time in the work area as a follow-up action history (step S308). Here, since the subject is focused based on a focus frame different from the focus frame that was defaulted in step S102 of the imaging process, the subsequent AF operation is performed based on a new focus position. Therefore, the follow-up processing unit 113 turns off the designated frame flag so that the next AF operation is reset (step S309), and the process returns to the imaging process flow shown in FIG.

  Such an operation is repeatedly executed while the shutter button 131 is half pressed (step S105: No). In other words, after the subject that was initially in the center position is focused by AF operation, when the subject is not in focus at that position due to the movement of the subject, the focus frame is searched from other focus frames, and the focus frame By performing pan / tilt operation so that the subject image at the center is in the center, framing is automatically performed so that the subject image is always in the center of the captured image while the shutter button 131 is half-pressed, In addition, the subject image is always in focus. In this case, since the framing is performed so that the subject is automatically centered by the rotation of the mirror 210, it is not necessary to move the main body of the digital camera 100 in order to center the subject.

  As described above, since the follow-up framing process is repeatedly executed, in the second and subsequent operations, the focus frame can be predicted based on the follow-up history so far and the framing can be performed. The operation of the tracking framing process in this case will be described again with reference to FIG. In the case of the second and subsequent operations (step S301: No), the follow-up processing unit 113 is constant in a certain direction, for example, based on the operation amount or direction of the previous or previous pan / tilt operation indicated by the follow-up operation history. If the pan / tilt is performed by an amount, it can be predicted that the subject will move to the position moved by the same amount in the same direction next time (step S310).

  When the next focusing frame is predicted in this way, the follow-up processing unit 113 instructs the optical system processing unit 114 to execute the AF operation in the prediction frame. The optical system processing unit 114 performs the same operation as that in steps S203 to S210 of the AF processing in the focus frame predicted by the tracking processing unit 113 (step S311). Here, if the subject is moving as predicted, focusing is performed in the prediction frame (step S312: Yes). In this case, by performing the processing after step S307, the frame is automatically framed by the pan / tilt operation so that the image of the focusing frame becomes the center of the captured image, and the flow of the imaging processing shown in FIG. Return to.

  On the other hand, when the focus is not achieved in the predicted frame (step S312: No), the subject has not moved as predicted based on the history, so the focused frame is searched by the processing of steps S302 to S306, and the searched focus is detected. A pan / tilt operation is performed so that the image of the focal frame is in the center of the captured image (step S306 and subsequent steps), and the flow returns to the flow of the imaging process shown in FIG.

  In this way, while the shutter button 131 is half-pressed, the subject image is automatically framed so that it is always in the center, and the subject is always in focus. The photographer fully presses the shutter button 131 when the desired shutter chance is reached while watching the imaging screen in which the subject is automatically following (step S105: Yes). In this case, the imaging processing unit 111 performs an imaging operation based on the shooting conditions (for example, shutter speed) at that time, and image data obtained thereby is stored in the captured image storage area 151 by the image processing unit 112. Stored. In this way, the still image pickup operation corresponding to the operation of the shutter button 131 is executed (step S106).

  In this case, if the fully pressed shutter button 131 is further pressed halfway (step S107: No), the processing from step S102 is repeatedly executed, and the follow-up framing operation is continued. Thereby, a plurality of still photographings (so-called continuous shooting) can be performed continuously while performing follow-up framing. That is, it is possible to continuously perform still photography while automatically framing the moving subject to the center without moving the digital camera 100.

  On the other hand, when the shutter button 131 is released (step S107: Yes), the still imaging by the tracking framing is finished. In this case, the tracking processing unit 113 controls the mirror unit 300 to return the mirror 210 rotated by executing the tracking framing process to the reference position (step S108), and is turned ON by executing the AF process. The designated frame flag is turned off (step S109), and the process is terminated.

  As described above, by applying the present invention as in the above embodiment, the digital camera 100 automatically follows the subject so that the moving subject is always at a predetermined position (for example, the center of the captured image). In addition to framing, an AF operation is performed so that the subject image is always in focus. Since such a follow-up operation is performed by the rotation of the mirror 210, the subject can be followed without moving the main body of the digital camera 100. Therefore, the occurrence of camera shake and image blur can be effectively prevented in a small and lightweight digital camera that is a bending optical type.

  The said embodiment is an example and the application range of this invention is not restricted to this. That is, various applications are possible, and all embodiments are included in the scope of the present invention.

  For example, in the follow-up framing process in the above embodiment, the case where the subject image is followed by searching for a focus position other than the default designated position (that is, the center frame) is exemplified. The method to do is not restricted to this, but is arbitrary.

  For example, as shown in FIG. 13A, a predetermined feature extraction area CA centered on a focus frame in which the subject image is focused is set, and the subject is determined based on the feature of the image corresponding to the feature extraction area CA. You may make it follow an image. In this case, when the subject image is focused at the default position (center position or the like) designated for the first time, the feature extraction area CA is set to extract the features. When the subject is not in focus at that position due to the movement of the subject, each feature is extracted from the feature extraction area CA corresponding to another focus frame, and the position indicating the same or similar feature as the first extracted feature is It is possible to set the subject position. In this case, if the pan / tilt operation is performed so that the position from which the feature is extracted becomes the center, the framing in which the subject is at the center position can be automatically performed as in the above embodiment.

  In this case, the feature of the image to be extracted is arbitrary. For example, as shown in FIG. 13B, the brightness, gradation value, or shading of the image in the feature extraction area CA can be extracted as a feature. it can. Alternatively, as shown in FIG. 13C, color information indicating a specific color constituting the image in the feature extraction area CA, a color difference component ratio, or the like may be extracted as a feature. Alternatively, as shown in FIG. 13D, the contour shape, area, center of gravity, and the like of the image in the feature extraction area CA may be calculated and extracted as features.

  Instead of these methods, for example, the movement position of the subject image may be predicted based on the movement vector of the subject image. In this case, for example, as shown in FIG. 14A, a predetermined vector detection area VA is set around the focus frame in which the subject image is focused, and the captured images are converted into a plurality of frame images continuous in time series. By performing the processing, as shown in FIG. 14B, the subject image shown in the vector detection area VA between frames can be compared to calculate the movement vector of the subject image.

  In this case, for example, as shown in FIG. 14C, the vector detection area VA can be divided into a plurality of sub-blocks to calculate a movement vector for each sub-block. For example, as shown in FIG. Then, the movement vector at the whole or center position of the vector detection area VA is calculated. Then, as shown in FIG. 14 (e), when the focus frame separated from the calculated movement vector is designated from the previously designated focus frame, and the pan / tilt operation is performed so that the focus frame becomes the center, Similar to the above embodiment, it is possible to automatically perform framing so that the subject is at the center position.

  In the above-described embodiment, the center portion of the captured image is designated as a focus target by default. However, the focus target position is not limited to this and is arbitrary. For example, the photographer may designate one of a plurality of focus frames, and framing may be performed by a pan / tilt operation so that the subject image is positioned at the designated focus frame. Thereby, it is possible to follow the subject with a composition according to the photographing intention of the photographer.

  In the above embodiment, the actuator for rotating the mirror 210 is configured by a voice coil motor. However, the present invention is not limited to this, and may be configured by, for example, a piezoelectric actuator or a bimorph type piezoelectric actuator. Further, the configuration for holding the mirror 210 shown in the above embodiment is merely an example, and the configuration for holding the mirror 210 may be used as long as the mirror 210 can be held for tilt rotation and / or pan rotation. It is not restricted to what was shown in the form, You may employ | adopt arbitrary things.

  In addition to the automatic follow-up operation shown in the above embodiment, a shake correction operation by rotating the mirror 210 is also performed. In this case, in the digital camera 100, a detection unit (for example, an angular velocity sensor) that detects movement around the horizontal axis and the vertical axis parallel to the X rotation axis and the Z rotation axis is provided. Blur correction can be performed by rotating the mirror 210 according to the value.

  In the above-described embodiment, the subject is automatically tracked when the digital camera 100 captures a still image. However, the subject tracking is not limited to still imaging, and the subject tracking described above may be performed when capturing a moving image.

It is a figure which shows the external appearance structure of the digital camera concerning embodiment of this invention, (a) shows the front of a digital camera, (b) shows the back of a digital camera. It is a figure for demonstrating the optical unit of the digital camera shown in FIG. 1, (a) is a figure for demonstrating the position of an optical unit, (b) is a figure which shows the structure of an optical unit roughly. is there. It is a figure which shows the detailed structural example of the optical unit shown in FIG. 4A and 4B are diagrams illustrating the configuration of the mirror unit illustrated in FIG. 3, in which FIG. 3A illustrates the configuration of the mirror unit viewed from the front direction of the digital camera, and FIG. . It is a figure for demonstrating the X rotation axis | shaft and Z rotation axis | shaft, pan rotation, tilt rotation, etc. in the digital camera concerning embodiment of this invention. It is a block diagram which shows the internal structure of the digital camera concerning embodiment of this invention. It is a functional block diagram which shows the function structure implement | achieved by the control part shown in FIG. It is a flowchart for demonstrating the imaging process performed in embodiment of this invention. It is a flowchart for demonstrating the AF process performed in the moving image imaging process shown in FIG. It is a flowchart for demonstrating the follow-up framing process performed in the moving image imaging process shown in FIG. It is a figure for demonstrating the follow-up framing operation | movement concerning embodiment of this invention, (a) shows the example of a display of a focus frame and the center frame designated by default, (b) focused the to-be-photographed object by the center frame. (C) shows a display example when the subject is no longer in focus at the center frame due to movement of the subject. It is a figure for demonstrating the tracking framing operation | movement concerning embodiment of this invention, (a) The example of a display at the time of searching a focusing frame is shown, (b) is the table | surface at the time of designating the searched focusing frame. An example is shown, and (c) a display example when the subject image is centered by tracking framing. It is a figure for demonstrating the modification of the tracking framing process concerning embodiment of this invention, (a) shows the example of the feature extraction area | region set based on a focus frame, (b)-(d) The example of the feature extracted in a feature extraction area | region is shown. It is a figure for demonstrating the other modification of the tracking framing process concerning embodiment of this invention, (a) shows the example of the vector detection area | region set based on a focus frame, (b) is between frames (C) and (d) show examples of movement vectors to be calculated, and (e) shows an example of a focus frame designated based on the calculated movement vectors.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Digital camera, 110 ... Control part, 111 ... Imaging processing part, 112 ... Image processing part, 113 ... Follow-up processing part, 114 ... Optical system processing part, 120 ... Photometry part, 131 ... Shutter button, 140 ... Display part, DESCRIPTION OF SYMBOLS 150 ... Memory | storage part, 151 ... Captured image storage area, 152 ... Program storage area, 200 ... Optical unit, 210 ... Mirror, 220 ... Lens unit, 230 ... Imaging element, 300 ... Mirror unit, 310 ... 1st holding body, 311 ... 1st actuator, 320 ... 2nd holding body, 321 ... 2nd actuator

Claims (8)

In a digital camera that obtains a captured image by imaging incident light bent by a reflector on an image sensor,
Drive means for rotationally driving the reflector;
Subject image detection means for continuously detecting a subject image shown at an arbitrary position designated on the captured image;
Subject tracking means for controlling the driving means and rotating the reflector so that the subject image detected by the subject image detection means is at a predetermined position on the captured image;
A digital camera comprising: An autofocus means for performing an autofocus operation based on parameters obtained from the captured image;
Focusing determination means for determining whether or not the captured image at the arbitrary position is in focus based on an autofocus operation by the autofocus means;
A focus position search means for searching for a position on the captured image that is focused by the autofocus operation when the captured image at the arbitrary position is not focused;
The subject image detection means detects the subject image by designating the position searched by the in-focus position search means as the arbitrary position;
The digital camera according to claim 1. Further comprising feature extraction means for extracting the features of the image at the arbitrary position;
The subject image detection means detects the subject image by designating the position of an image showing the same or similar feature as the feature extracted by the feature extraction means as the arbitrary position;
The digital camera according to claim 1, wherein the digital camera is a digital camera. Further comprising vector detection means for detecting a movement vector between a plurality of frames of the image at the arbitrary position;
The subject image detection means detects the subject image by designating the arbitrary position based on the movement vector detected by the vector detection means;
The digital camera according to claim 1, wherein the digital camera is a digital camera. Subject image prediction means for predicting the movement position of the subject image based on the detection history of the subject image by the subject image detection means;
The subject image detection means detects the subject image by designating the position predicted by the subject image prediction means as the arbitrary position;
The digital camera according to claim 1, wherein the digital camera is a digital camera. The subject image detection means detects the subject image based on the arbitrary position specified by a plurality of focus frames set on the captured image;
The digital camera according to any one of claims 1 to 5, wherein: The driving means includes
First rotating means for rotating the reflector in a vertical direction on the captured image;
Second rotating means for rotating the reflector in a lateral direction on the captured image,
The subject tracking means controls the first rotating means and the second rotating means to rotate the reflector so that the subject image is at a predetermined position on the captured image.
The digital camera according to claim 1, wherein the digital camera is a digital camera. The subject tracking means rotates the reflector so that the subject image is at the center position of the captured image.
The digital camera according to claim 1, wherein the digital camera is a digital camera.

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